Keio University

The Texture of the Japanese Room

Publish: October 15, 2025

Participant Profile

  • Eiko Matsui

    Other : ArchitectOther : Representative of Matsui Architectural Design OfficeFaculty of Business and Commerce Graduate

    Graduated from Keio University Faculty of Business and Commerce in 1972. Graduated from the Department of Architecture at the University of Stuttgart, Germany. After working at an architectural firm, returned to Japan in 1985. Since then, has worked on numerous wooden houses and folk house renovations.

    Eiko Matsui

    Other : ArchitectOther : Representative of Matsui Architectural Design OfficeFaculty of Business and Commerce Graduate

    Graduated from Keio University Faculty of Business and Commerce in 1972. Graduated from the Department of Architecture at the University of Stuttgart, Germany. After working at an architectural firm, returned to Japan in 1985. Since then, has worked on numerous wooden houses and folk house renovations.

  • Machiko Hoshina

    Other : Tea MasterOther : Urasenke ProfessorFaculty of Letters Graduate

    Graduated from Keio University Faculty of Letters in 1995. Studied under Urasenke Honorary Master Sōmei Mori, and has provided tea ceremony experiences to over 10,000 people in Japan and abroad, including at embassies and international conferences. Dedicated to the mission of spreading tea ceremony and Japanese culture.

    Machiko Hoshina

    Other : Tea MasterOther : Urasenke ProfessorFaculty of Letters Graduate

    Graduated from Keio University Faculty of Letters in 1995. Studied under Urasenke Honorary Master Sōmei Mori, and has provided tea ceremony experiences to over 10,000 people in Japan and abroad, including at embassies and international conferences. Dedicated to the mission of spreading tea ceremony and Japanese culture.

  • Fumio Kuboki

    Other : Representative of Kuboki Tatami ShopFaculty of Science and Technology Graduate

    Graduated from Keio University Faculty of Science and Technology in 2012. After working for a construction company, inherited the 280-year-old family business in 2020. Promoting the appeal of tatami as a traditional Japanese industry to domestic and international audiences from bases in Tokyo and Fukushima Prefecture.

    Fumio Kuboki

    Other : Representative of Kuboki Tatami ShopFaculty of Science and Technology Graduate

    Graduated from Keio University Faculty of Science and Technology in 2012. After working for a construction company, inherited the 280-year-old family business in 2020. Promoting the appeal of tatami as a traditional Japanese industry to domestic and international audiences from bases in Tokyo and Fukushima Prefecture.

A Tea Ceremony Open to Everyone

Matsui

Washitsu (Japanese-style rooms) generally refer to wooden structures built using traditional Japanese construction methods, which have existed for over a thousand years. Today, these old wooden buildings are being demolished one after another. Tatami mats are also a unique Japanese element that has existed since ancient times.

Kuboki

That's true. They are said to have existed since the Nara period, so they have a history of over 1,300 years.

Matsui

When I was a child, it was natural to sleep and wake up in a washitsu, and it was the place where relatives gathered for socializing. That way of living is a Japanese treasure built by carpenters and craftsmen with experience and skill.

Unlike the rigid wall structures of Western countries, traditional Japanese construction is characterized by its flexibility. However, these techniques that lasted for hundreds of years began to disappear rapidly after the war, replaced by factory-produced Western-style prefabs and the like.

Hoshina

I also want to protect the fading traditional culture of Japan through my beloved tea ceremony. I entered the Graduate School of Tokyo University of the Arts in 2023 and am studying in the Department of Arts Studies and Curatorial Practices. Recently, I have been experimentally hosting tea ceremonies called "Zaifu."

Zaifu was a form of tea ceremony that continued until around the Meiji and Taisho periods. When a sign saying "Zaifu" was placed under the eaves of a tea master's house, it was a sign of an open tea ceremony that anyone could join. Upon entering the house, one could enjoy a bowl of tea prepared with traditional etiquette. I started this at "Nakamachi no Ie," a 110-year-old traditional house managed by the university, to see what would happen if we revived such stylish hospitality in the modern era.

Matsui

That's interesting.

Hoshina

"Nakamachi no Ie" was originally a private house built in the Edo period that collapsed during the Great Kanto Earthquake and was rebuilt in the Taisho period using the original timber. Usually, artists use it as a creative space with free ideas.

When I set up a tea ceremony in this building, Gen Z youth gathered there. It became a place where people who entered out of curiosity enjoyed accidental encounters, and they were able to learn that tea, which they thought had a high threshold, is actually familiar, warm, and fun.

When I realized that, I felt that digital native youth are seeking real experiences somewhere. When I announce on Instagram that I'm doing a "Zaifu," they catch it and spread it. I see a bright sign there.

Kuboki

So, the classical space of the Taisho period is popular with Gen Z.

Hoshina

I intentionally don't turn on the lights during practice, and perhaps that kind of extraordinary setup was good. When you are in a dim space, strangely, your other senses become sharpened. Looking at the history of tea, there was no culture of brightly illuminating the tea room with lights. Conversely, it means we usually rely too much on visual information.

Flexible Traditional Japanese Construction Methods

Matsui

As an architect, I have worked on the restoration of old folk houses, and people who wish to revive their homes for the next generation all have strong feelings. Consultations from foreign residents are increasing, and there is a need for people to fix things with their own hands.

Hoshina

The number of people who desire a daily life that takes time and effort is increasing. That is probably being accepted as a luxury.

Matsui

Foreigners say they don't mind the cold. They say it's not inconvenient compared to the quality of the environment.

Hoshina

Everyone finds the inconvenience amusing, don't they?

Matsui

While preserving as much of the old material as possible, we perform restoration work to improve earthquake resistance and habitability suited to modern life so that people can continue to live there with peace of mind.

Hoshina

"Nakamachi no Ie" has issues with its seismic structure, and the university is having a bit of trouble handling it.

Matsui

Since traditional houses have a flexible and tenacious seismic isolation structure, they have few shear walls and often do not meet current seismic standards, so seismic measures are necessary.

The key is to provide earthquake resistance while utilizing the structure unique to traditional methods. In particular, the pillars are called "Ishibadate," and they simply sit on top of the foundation stones. They shift over time, but this shifting absorbs the force.

Furthermore, the upper structure maintains flexibility through the carpenter's high-level timber framing techniques. Because it is not fixed too rigidly with metal fittings, the framework moves flexibly, preventing collapse.

Hoshina

I see. That's easy to understand.

Matsui

Therefore, in places where shear walls are needed, instead of making them rigid with modern structural plywood, we install wooden frames with "nuki" (horizontal penetrating ties) between existing pillars to allow for a little sway.

Hoshina

So you update it in a way that doesn't impair the flexibility of the traditional building.

Matsui

Exactly. It's easy if you use modern structural plywood and adhesives, but the overall balance is lost, and the merits of traditional methods where Japanese craftsmanship shines are impaired.

It is said that washitsu are decreasing in Japanese homes due to renovations, but in fact, the restoration work for a washitsu is quite difficult. It is harder to take a wooden house with a "shinkabe" structure (exposed pillars and beams), improve its earthquake resistance and habitability, enhance insulation, and then return the room to its original state than it is to change it into a Western-style room.

Hoshina

It sounds like it would be costly, too.

A person from the US who restored an old house in Kamakura is tall, so they raised the ceiling by about a dozen centimeters. When I was invited inside, it felt strange. The tatami mats were probably the standard dimensions, but the balance of the ceiling height was different from the washitsu we are usually familiar with.

Matsui

I think that's because the dimensions of a washitsu, such as the size of fusuma and shoji, are based on the tatami mats. The ceilings and fixtures of a washitsu are kept low, which is probably too low for Westerners. There's the inconvenience of hitting one's head, but I sometimes wonder if they couldn't just lower their heads to pass through rather than changing the dimensions (laughs).

The Story Within the Materials

Hoshina

The dimensions of tatami have been said to be 90 cm x 180 cm since long ago.

Kuboki

One mat is six shaku by three shaku. Two mats make one tsubo, but tatami dimensions have changed over the eras. The standard of six shaku equaling one ken originates from when Tokugawa Ieyasu changed the dimensions to impose more taxes when surveying the area of rice fields, which was the basis for tax rice.

Kyoma and Edoma are the known tatami dimensions; Kyoma is larger, and there is also Chukyo-ma, which is slightly smaller than Kyoma. The dimensions set by Ieyasu are called Edoma, and it is said that as the tax rate for rice increased, the unit of tatami dimensions became smaller.

Hoshina

I also heard that the spaces in townhouses are long and narrow like a "eel's nest" because the tax paid differed depending on the width of the storefront.

Kuboki

It's interesting. Chukyo-ma is also known as a reference scale, and the inner dimensions between pillars are sometimes called that.

Matsui

Converting Edoma to centimeters gives 176 cm. There are many cases where the height of the fusuma is also set to 176 cm.

Kuboki

176 cm is five shaku and eight sun.

Hoshina

The way of counting in shaku is one of the important things we must preserve.

Matsui

We still use shaku for designing washitsu. We talk to the carpenters in shaku, but we talk to the clients in centimeters.

Hoshina

So designers are bilingual.

Matsui

You can't do the job unless you understand both. But I think the number of young designers who don't use shaku is increasing. Though I believe those who work on traditional wooden architecture have it ingrained in them.

This dimensional system is also used during the process of "kidori," or cutting out the timber. If you try to make the ceiling height high like that American person living in Kamakura, ordinary residential timber probably wouldn't fit.

Hoshina

Various types of wood are used in tea rooms. A characteristic is that it creates an effect almost like forest bathing.

Matsui

Tea rooms use carefully selected solid wood, don't they?

Hoshina

Yes. Each piece of wood, especially the material for the tokobashira (alcove post), always has a story, and at a tea ceremony, we enjoy the flavors of various woods while listening to those stories.

Actually, when it came time to rebuild my house, I absolutely had to cut down a cherry tree in the garden. It was nearly 100 years old and a tree the family enjoyed for flower viewing every year, so it was very regrettable, but I was able to have it refashioned into the tokobashira for my home tea room.

Kuboki

That's a wonderful story.

Hoshina

Cherry is not that expensive as a wood, but for the family, it was a tree with precious memories. Materials have stories, and that is why they have value. I felt that creating personal value is also important.

From Goza to Oki-tatami, and then to Washitsu

Hoshina

How did tatami evolve into its current form?

Kuboki

Actually, 1,300 years ago, floor coverings were "goza" (straw mats). They were spread out on wooden floors, but because they were "folded and put away" (tatande-oku), they came to be called "tatami." In the Heian period, thick tatami that only high-ranking people could sit on were born, and the style changed to "oki-tatami" (placed mats) in the living rooms of Shoin-zukuri architecture.

Hoshina

Like the ones for Hina dolls.

Kuboki

Exactly. It became an area where only high-ranking people could sit, and eventually, tatami-beri (borders) appeared. Patterns representing the rank of the high-ranking person were depicted on the borders.

The well-known "Ungen-beri" is a tatami border for the Imperial Family, and there was also Korai-beri for the nobility. The reason you must not step on the tatami border is that it bears important patterns indicating rank.

Matsui

I see!

Kuboki

The culture of oki-tatami lasted for about 800 years. It was about 500 years ago that they began to be laid out to cover the whole floor as they are now. With the rise of Shoin-zukuri and Sukiya-zukuri, it changed from oki-tatami to the washitsu.

Hoshina

The tea room "Taian" built by Sen no Rikyu in Yamazaki, Kyoto, must have been a breakthrough in the history of tatami. In a tea room of only two mats, people would remove their swords and bow their heads to enter through the "nijiriguchi" (crawling-in entrance) to enjoy tea regardless of social status.

Matsui

It's amazing how such a condensed space was conceived. The furnishings of a washitsu are designed to match the state of sitting in seiza (kneeling). The eye level when sitting serves as the dimensional standard (module) for a traditional washitsu. When you sit in seiza and look at the garden or observe the interior furnishings, you can feel the space of the washitsu come alive.

Hoshina

I agree.

Matsui

By experiencing a washitsu, there is a sense that something Japanese people hold at their roots is awakened. Isn't tatami the foundation of "Wa" (Japanese harmony)?

Kuboki

I'm happy to hear you say that.

Hoshina

Despite that, so many people live in spaces without tatami. In the world of tea, since the Meiji period, the "Ryurei" style—the etiquette of preparing tea at a table—was devised. This is also a symbolic example of Westernization in Japan, but I usually recommend the experience of tea on tatami. Since many foreigners' legs go numb from sitting in seiza, I tell them it's okay to relax their legs. This is because I want them to lower their eye level in the tea room.

By physically lowering their eye level, they notice the amount of information the tea room holds. Then, they can notice things like the scent of rush grass and incense, the sound of boiling water and the steam, and the hanging scrolls and flowers in the tokonoma.

Kuboki

So there are things you can't see in the Ryurei style.

Hoshina

Yes. I hear that for Taian, the view from the nijiriguchi is crucial. Once inside, it is an ultimate personal space that could even be called a work of craft, and you can only enjoy the view of the space at the moment you put your body into it. Inside the tea room, you become a part of it. I think the concept of the nijiriguchi, which focuses the gaze on a low point for appreciation, is incredible.

Facing Each Other Across the Tatami Border

Hoshina

In such a small space, I believe the tatami borders (heri) serve as a boundary (kekkai). In a two-mat tea room, you face your superior across these borders.

I ask international visitors who come for a tea ceremony experience to look at the weave of the tatami and count 16 rows from the border. At first, they are surprised, but when I explain that when your knees reach the 16th row, it is the perfect dimension to place the tea bowl inside the border and bow with your hands on the floor, they are convinced.

Kuboki

It is said that one row of the tatami weave is 1.5 centimeters, and two rows make one 'sun' (a traditional unit of measurement). In other words, Issun-boshi (the Inch-High Samurai) is about 3 centimeters tall (laughs).

Hoshina

I've heard that unsui (monks in training) used to use a single tatami mat in the monk's hall as their place to live and sleep. From ascetic training and tea ceremonies to the lives of ordinary people, we can see that tatami served as a standard for distance. Even in a regular tea ceremony, the tatami border acts as a boundary for communication between the host and the guest. The host brings the tea or sweets right up to the edge of the border, and it is the guest's role to cross that boundary and bring them to their own side.

By visualizing the place where each other's worlds meet as a border, I think a space is established where etiquette exists even among close acquaintances. Tai-an is likely the ultimate form of that. It is a distance that carries quite a bit of tension, but hospitality within that space must be a superlative experience.

Wanting to Eat Tangerines in a Japanese-style Room

Matsui

Seiza (kneeling) puts a strain on the knees, so it tends to be avoided by the elderly, but since I am learning Noh chanting (utai), I can do seiza without any burden. I practice by facing my teacher one-on-one, sitting in seiza directly on the tatami. Since chanting involves abdominal breathing and putting strength into the stomach to project the voice, I lean forward slightly.

Hoshina

The core of Japanese people, who wore traditional clothing and walked in zori (sandals) in Japanese-style rooms, was originally inclined slightly forward. Even when sitting in seiza, they leaned slightly forward, and if you look at Hokusai's ukiyo-e prints, everyone is walking with a forward lean. Walking by leading with the heel probably started because we began wearing shoes.

As the posture of Japanese people changes, acquiring beautiful movements through traditional arts becomes a form of value in itself. Being able to switch your core—wearing high heels stylishly one moment, and walking with a pigeon-toed stride from the toes in traditional dress the next—is a skill. Acquiring such skills or living a life with a Japanese-style room is becoming a status symbol.

Matsui

I think time spent in Japanese-style rooms will attract attention again. For my final home, I would like a wooden house built with traditional methods that has a Japanese-style room. It is wonderful to be able to spend special time looking at the garden from a floor chair or sitting in seiza on thick tatami mats.

Hoshina

On the other hand, some seniors say that once they get used to a lifestyle with chairs, they can no longer take the posture of sitting on the floor. There are various hurdles, such as not being able to stand up or finding it painful because their ankles are stiff. I wonder what we can do to help people become familiar with Japanese-style rooms in their daily lives.

Matsui

There are many people who want a Japanese-style room with a kotatsu. Not just in old folk houses but even in new constructions, they say they want to eat tangerines together, even if the room is only four-and-a-half mats in size.

Hoshina

That sounds lovely.

Matsui

Japanese-style rooms are also convenient for family members living away to stay in when they come home, and I suppose many different uses can be imagined.

Kuboki

Actually, I once received an order for tatami from a Japanese person living in the United States. When I asked how they intended to use it, they said they wanted to eat tangerines at a kotatsu (laughs).

Matsui

Tangerines in a Japanese-style room is truly a form of family togetherness.

How to Pass on the Tokonoma

Hoshina

Aren't tokonoma (alcoves) also gradually disappearing from Japanese homes? I feel that the things Japanese people have cherished are becoming fundamentally harder to see. I believe the role of Japanese spaces was also to visualize elements of communication through forms like tatami borders or the nijiriguchi (crawling-in entrance) of a tea room.

Kuboki

That is certainly true.

Hoshina

Every house used to have a tokonoma, and it served a role not just for displaying hanging scrolls or flowers, but also for creating relationships by having guests or the head of the household sit near it.

Matsui

The tokonoma is usually in the inner guest room (okuzashiki), and we often receive requests from people who definitely want to keep it.

Hoshina

So the tokonoma is becoming a rarity. What I feel while raising children is that there is so much we can teach the next generation about the spaces we live in every day.

However, children today have no concept of a tokonoma, so it is difficult to convey that it is a sacred place and a space that shapes relationships within the home. I wonder if our generation can pass on the cultural baton. I even heard a story about a student who saw tatami for the first time on a school trip and, without knowing better, stepped onto it while still wearing slippers.

Matsui

I think it would be good to occasionally hold primary and secondary education classes in a Japanese-style room. I graduated from Keio Girls Senior High School, and while I was a student, there was a wooden house on the grounds that was formerly the residence of Count Satotaka Tokugawa. We spent time relaxing in that Japanese house, and tea ceremonies were sometimes held there.

Hoshina

It seems the role of the Japanese-style room as an educational tool still has a lot of potential.

Can Tatami Take Flight into the World?

Matsui

I believe tatami is an important element that presents a Japanese-style room as a special space. Inside the Westin Miyako Hotel Kyoto, there is a sukiya-style annex called Kasuien, designed by the architect Togo Murano, who was known as a master of Japanese-style rooms. It is a wonderful space where every room has a corner window to view the garden, but apparently, Japanese guests are gradually decreasing while inbound tourists are increasing.

Recently, these Japanese-style rooms were updated to fit modern lifestyles by adding low beds and such. However, the floors remain tatami, and the essential point of the Japanese-style room—lowering one's line of sight—is preserved.

Kuboki

Recently, we have been proposing styles that combine spaces featuring tatami with Scandinavian furniture.

Matsui

Tatami and Scandinavian furniture seem like they would go well together.

Kuboki

In terms of natural materials, the raw material for tatami is rush (igusa), so it goes well with wood. Using the fact that it brings wellness and peace of mind as a strength, we aim to create spaces that make people think, 'I want to live like this.'

Matsui

Tatami seems like it would be popular abroad as well.

Hoshina

The fact that it can be easily removed is another good thing about tatami. In a tea room, the hearth (ro) is opened or closed depending on whether it is summer or winter, so this ease of use is truly functional.

I think it would be great to have portable sizes; what do you think? There is actually someone making quarter-sized tatami mats, which are convenient for displaying tea bowls and other items overseas. The tatami maker who produced these used them for changing a baby's diaper or letting them take a nap.

Kuboki

We also make small tatami mats that can be placed on a table. In recent years, as Japanese cuisine has spread worldwide, it has become possible to eat Japanese food even in the restaurants of luxury hotels abroad. We created these while imagining scenes where guests might enjoy matcha after a meal. They are actually being provided at a hotel in New York and have been well-received.

Hoshina

Even just having a small piece there seems like it would turn a dining table into a Japanese space.

Matsui

It might also help Japanese travelers and those living locally to rediscover Japanese culture.

Hoshina

True. Japanese people are susceptible to things that are 're-imported,' so I think some people would be pleasantly surprised (laughs).

How to Communicate Japanese-style Room Culture

Kuboki

Do you feel a momentum for 're-importation' in places like tea ceremonies?

Hoshina

I do. The reaction is particularly good among young Japanese people who have been educated abroad.

Matsui

I also rediscovered the wonderfulness of Japanese culture after returning from Germany.

Hoshina

If you stay in the country all the time, it might be too ordinary to notice. Recently, more families are sending their children to schools overseas. Those children not only acquire language skills and a global perspective, but by becoming a minority for once, they seem to become more aware of Japan.

Also, through interacting with international visitors through tea, I feel that interest in Japanese culture is currently incredibly high. I almost feel that there isn't enough communication coming from Japan.

Kuboki

Ms. Hoshina, what do you keep in mind when conveying Japanese culture to inbound visitors?

Hoshina

I have been familiar with tea since childhood, but the catalyst was my experience studying abroad as a student. The tea culture that had become ordinary to me was received as something very unusual abroad. I felt a frustration at not being able to put that into words.

On the other hand, after graduating from university, while busy with work, marriage, and child-rearing, I felt that the tea room and Japanese spaces were places where I could return to my true self. A space for meditation, or a place to center oneself. These two experiences overlapped, and I decided to thoroughly verbalize things like the 'reading between the lines,' the 'ma' (space/timing), and the 'kata' (forms) through 'English Tea Ceremony.' Since tea is a world of subtle implication, I thought it might be excessively unrefined to do so, but when I tried it, the resolution of my understanding of the space and manners improved dramatically.

Kuboki

That is very important.

Hoshina

I found that by putting it into words, it not only made sense to me, but it could also be conveyed to those without prior knowledge. By translating it into another language, I rediscovered the beauty of the Japanese language, and I was able to re-recognize words of sensibility that are different from logical explanations.

Matsui

The nuances must be fundamentally different.

Hoshina

Yes. However, unless we somehow translate that, it won't reach people from other countries. Also, the process of thinking about it leads to knowing oneself, so it is very interesting.

Matsui

That is interesting. I imagine there aren't many people who think that deeply about it.

Hoshina

But I think the number is increasing. I believe the driving force for people trying to take on challenges is an internal motivation—because they like it. In that sense, inbound visitors come all the way to Japan and provide us with a very good opportunity.

Kuboki

That is exactly right.

Hoshina

There are countless places to travel in the world, yet they come to Japan and even participate in tea ceremony experiences. At that point, we are already very compatible.

"What's So Good About Tatami?"

Kuboki

I also have a strong interest in conveying culture through words. This is because five years ago, when I went to the U.S. to try to spread tatami to the world, I had a very frustrating experience.

I went around doing cold calls, but when I was asked, "What's so good about tatami?" I could only say things like "It's somehow relaxing," and I was at a total loss. But that wasn't a language barrier; it was because I didn't have the words within myself to convey it properly. I realized that if I couldn't explain it in Japanese, there was no way it would be understood abroad.

Hoshina

That was a valuable experience.

Kuboki

Using this experience as motivation, I started going into the rice fields to observe the materials and learning about the aromatic components. I felt the need to clearly convey what constitutes the true appeal of tatami. Consequently, I opened a showroom in Ginza last year, and I discovered that there are not only inbound visitors but also Japanese customers who are rediscovering Japanese culture.

Hoshina

"A new discovery for foreigners, a rediscovery for Japanese" is my recent catchphrase.

Kuboki

Exactly so.

Matsui

Do you talk with the employees of Kuboki Tatami Shop about protecting tradition and Japanese culture?

Kuboki

Yes. While we have an awareness of wanting to protect the culture, tradition alone won't make people want tatami. We talk about how to communicate the value of tatami.

Matsui

For example, how about the idea of laying tatami in nurseries? I think it would be very good for taking naps. There are quite a few facilities using old folk houses as nurseries.

Kuboki

That's a great idea. In Sukagawa City, Fukushima Prefecture, we renovated a building that used to be a Kuboki Tatami Shop factory and opened an experiential complex called Tatami Village in 2023. We hold events for children there, and tatami is very well-regarded by families raising children.

Matsui

It's safe for children, too.

Kuboki

At the Tatami Village cafe, there are benches designed in the image of an engawa (veranda). Mothers with small children can be seen having tea while letting their babies lie on the tatami. We also tried making coasters out of tatami omote (woven rush grass).

Hoshina

That sounds lovely!

Kuboki

We are also conducting various experiments using tatami. For the cafe benches, we created tatami with geometric patterns rather than the standard 6-foot by 3-foot shape.

Matsui

That's innovative. Is it something that can be made easily?

Kuboki

It's not easy. It was quite a challenge to make them fit the shape of the benches perfectly.

Hoshina

Because they are custom-made. Thinking about it that way, you realize that the size of a single tatami mat has become the standard for the Japanese sense of dimension. Is it still more rational in terms of the manufacturing process to produce them in the 6-foot by 3-foot size?

Kuboki

Yes. Since the shaku-sun measurement system is the basis, the tools are also made in multiples of approximately 30 centimeters.

Yoga on Tatami?

Kuboki

Actually, the production of igusa (rush grass) is currently decreasing across Japan. The supply of domestic tatami omote has decreased by 72% over the past 20 years. Over 95% of igusa production is in Kumamoto Prefecture; while Hiroshima and Okayama used to be major production areas, the number of producers is decreasing every year. The number of igusa farmers fell below 300 two years ago, was 260 last year, and is 220 this year. I want to do something to stop this.

Hoshina

Is the rest imported?

Kuboki

Mainly from China. The challenge for the tatami industry is that it has gone too far into price competition. Good tatami is not circulating much.

When you try to make it cheaper using plastics or chemical fibers, the quality naturally drops. One aspect of tatami quality is durability. Thin igusa is weak against friction and quickly wears down and frays. If people use such products, they start to dislike tatami itself, leading to a vicious cycle where people move away from Japanese-style rooms.

Hoshina

Conversely, you could say that domestic igusa has high scarcity. It makes tatami spaces seem like something luxurious. Being able to enjoy the texture of tatami in daily life might be a form of richness.

Kuboki

That's true. In the tatami industry, we often talk about how to provide value so that customers will want tatami. However, the existence of tatami was so commonplace that I never imagined it would become something luxurious.

Matsui

The feel against the soles of your feet is also something you can only experience with tatami. Tatami also has a humidity-regulating effect, and in a house where I previously worked on restoring a traditional folk house, the owners used the Japanese-style room as a piano room for their child. They said it was calming.

Kuboki

Tatami also has soundproofing effects.

Hoshina

To help people enjoy tea more casually, I once held a session where I served tea after having them do yoga in a Japanese-style room.

Matsui

Yoga on tatami?

Hoshina

I had them enter the tea room in their yoga wear and entertained them with a tea ceremony. Many people hesitate because of things like wearing a kimono or learning etiquette, so I wanted to remove those rules and extract only the positive experience. It felt old yet new for Japanese people, and for foreigners, it provided a sense of Japanese-style wellness, and it was very well received.

Kuboki

A tea ceremony after yoga... that sounds very relaxing. Wellness is an important keyword when talking about the appeal of Japanese-style rooms.

Actually, igusa is said to have a relaxing effect because it contains vanillin, a component of vanilla essence. Furthermore, it contains a lot of phytoncides, which are forest components that provide the relaxation effect obtained from forest bathing. Freshly harvested igusa is very green, and I think it is also visually soothing.

How to Make Tatami Last Longer

Hoshina

Are there any maintenance tips for making tatami last longer?

Kuboki

While durability largely depends on the quality of the material, the best thing is to vacuum or clean it frequently. When we deliver new tatami, we tell customers to "vacuum along the grain of the tatami" or "if you spill a drink, dab the stain with a wet cloth to remove it."

Some people think it's good to wipe it with a wet cloth, but actually, giving it too much water can cause it to rot. It's better to wipe it with a dry cloth along the grain to bring out a beautiful luster.

Matsui

Because igusa is breathing.

Kuboki

That's right. Human oils can actually be better for tatami than water.

Matsui

In that sense, the same goes for pillars and earthen walls. The materials in a Japanese-style room are breathing. Good pillars gain color and character as they are used.

Hoshina

Exactly. The alcove post in the Ohashi Saryo tea room in Akasaka shines black where the master's head would be. Over years of use, it became shiny from hair oil. That's also part of its charm.

The Challenge of the Mobile Tea Room

Hoshina

At the Rengo Mita-kai on October 19, we will create a mobile tea room at the Raiosha on the Hiyoshi Campus and hold a tea ceremony. A shrine carpenter will come to build a two-mat tea room modeled after the Taian starting that morning, and we will hang the "Oikama" sign, so please do come.

Matsui

That's wonderful!

Kuboki

Have the tatami mats for the mobile tea room been decided? I have the best igusa in Japan, harvested from fields in Kumamoto.

Matsui

Amazing. What is the best igusa in Japan like?

Kuboki

Above all, it is durable. It lasts a long time and never frays. And it tans beautifully.

Two years ago, I delivered tatami using this igusa to the former residence of Eiichi Shibusawa in Fukaya City, Saitama Prefecture. When I went to see it recently, it had tanned very beautifully. Good igusa is densely packed, so it results in a very soft finish.

Matsui

I would definitely like to sit on that. Good tatami feels different to sit on. It's fluffy, making it harder for your legs to go numb, and it's perfect for taking a nap.

Hoshina

I definitely want it in the mobile tea room too... (laughs).

At the Rengo Mita-kai, we will also show the assembly process, so people can enjoy the woodworking techniques, the lightness of the architecture, and the flavor of the materials. With the cooperation of the Forestry Mita-kai, we will be provided with thinned wood from various "Keio Forests." In the future, I hope to propose a tea room using thinned wood from the "Keio Forests."

Kuboki

That's a wonderful story.

Hoshina

In the past, the value of a tea room was based on the lineage of the wood, such as knot-free solid precious wood. In today's era where sustainability is the goal, I think there is significance in actively utilizing materials that would otherwise be discarded. I hope to have shrine carpenters select good materials and use them as "cultural precious wood."

Matsui

That's an interesting idea.

Hoshina

Since the mobile tea room can be relocated, I want everyone to use it. Recently, I started a cultural salon called "Fujibakama" using an old folk house in Nihonbashi Ningyocho with some Keio colleagues. I actually installed a two-mat mobile tea room in that space.

Kuboki

It's really expanding.

Hoshina

In March this year, we showcased it on a large scale at the Haneda Airport Garden in the Haneda Airport International Terminal. It was a project to propose Japanese culture as a work of art, and there was a response not only from inbound tourists but also from people in Japan.

Kuboki

That's amazing. I would definitely like to collaborate. How about a performance where a carpenter assembles the tea room on-site and a craftsman from Kuboki Tatami Shop sews the tatami omote?

Matsui

I'll reach out to my friends and people at the Japan Association for the Regeneration of Traditional Folk Houses as well.

Hoshina

Great! Let's all do it together.

Recorded on September 4, 2025, at the Mita Campus

*Affiliations and titles are as of the time of publication.

A Casual Conversation among Three

Showing item 1 of 3.

A Casual Conversation among Three

Showing item 1 of 3.