Interviews met Tsukasa Ono

I am a Japanese architect and the founder of tono Inc. After working in architectural design in Tokyo for many years, I moved to Yakushima Island in 2020 and began exploring regenerative architecture. Today, my work focuses on creating architecture that enriches people’s lives while restoring the natural environment.

tono is a regenerative architecture studio based in Yakushima, Japan. Through architecture, interiors and spatial design, we aim to enhance biodiversity, human wellbeing and long-term environmental value.

For me, design is a way to improve the relationship between people and nature.

I want to design ways of living in which humans become part of the ecosystem. For this reason, I especially enjoy designing homes and hospitality spaces that support such a way of life.

Sumu Yakushima is one of my most meaningful projects. It demonstrates that the act of living itself can contribute to the recovery of nature.

In my previous career and in the early years of tono, I designed many shared houses and shared offices. Through those experiences, I learned that design is not only about creating visually attractive spaces, but also about transforming people’s emotions and experiences.

I like natural materials, especially local timber, earth and stone. I also use civil engineering techniques inspired by traditional Japanese wisdom that help architecture coexist with nature.

There are two moments. I receive inspiration when I am in the forest or near water. I find the words and ideas to express it through dialogue with collaborators.

I focus on harmony between architecture, nature, ecosystems and human happiness.

I feel curiosity and hope.

When I see people and nature becoming richer together, I feel deep gratitude.

A successful design creates multiple positive impacts at the same time for people, society and the environment.

I consider whether the design is not only functional and easy to use, but also carries a message strong enough to change the values of the people who experience it.

Design can be considered complete if it fulfills the requested function. However, architecture affects people’s safety and health, as well as the natural environment. I believe designers are responsible for understanding these wider contexts and giving them form.

I believe design is moving beyond sustainability toward regeneration. The future will be one in which humans and nature become more deeply integrated.

In 2026, my work was exhibited in Italy and other places. From July this year, I will also participate in “Constellation Resonance — 2026 Asia Social Design Exhibition” at the Red Dot Design Museum Xiamen in China. I hope to continue introducing regenerative architecture around the world.

Nature is my greatest teacher.

I value simplicity by removing unnecessary elements. When natural materials, light and the surrounding landscape are brought into harmony, the design is complete.

Yes. Japanese craftsmanship and respect for nature strongly influence my design. Living in Yakushima has deepened this perspective even further.

I collaborate with companies from concept development and design strategy through to realization.

It is important to choose a designer who can share your long-term vision, not only respond to immediate requirements.

First, I observe, listen and understand the ecosystem of the site. Then I consider how to harmonize it with the client’s vision and needs.

A Nychair X rocking chair, a Cestita Alubat table lamp, a HASAMI PORCELAIN mug, a Leica camera and a grid notebook.

While based in Yakushima, I live as if I am traveling around the world. My daily rhythm changes depending on where I am, but I usually communicate online with my team and clients, engage with the nature of each place, and deepen my thinking on regeneration.

Stay curious and keep learning from nature. Even when things seem complex, the answers found in nature are often very simple and elegant.

The positive side is that design allows you to see the world from a broader perspective. The difficult side is that you must keep questioning. You cannot simply compromise with “this is good enough”; you must continue until you reach the answer that feels like “this is the only way.”

My golden rule is to listen not only to people, but also to nature and to the building itself, in order to discover what form it should take.

Observation and insight—the ability to notice subtle differences. This includes not only differences in form and color, but also invisible qualities such as sound, atmosphere and the feeling of the air.

A grid notebook, erasable ballpoint pens, an iPhone and a laptop computer.

Because I travel often, I try to secure time to think alone.

It depends on the scale, but a project usually takes from one year to several years. I am often involved from the concept stage or even from the search for a site, and some projects have already continued for around five years.

“Can architecture really restore nature?”

Moving to Yakushima and making a major shift toward regenerative architecture was the most important experience in my career.

I work with private homeowners, hotels, developers, companies and organizations that aim to regenerate the environment.

I enjoy projects that can become models for the future of living.

I want to expand regenerative architecture internationally and help establish it as a new standard for architecture.

As a company, tono is led by me alone. However, I define the creative direction and collaborate with specialists from many different fields to realize each project.

Several regenerative architecture projects are currently in progress in Japan and overseas.

People can contact us through our website or by email.

https://www.to-no.me/

info@to-no.me

There is a phrase I like: “We are not on Earth, we’re Earth.” I believe humans are not only beings that continue to place a burden on the environment. As part of the Earth, we can also become beings that actively restore the environment. What matters is not to deny humanity or even ego, but to imagine architecture while staying close to nature.

Before moving to Yakushima, I had already begun to feel uncomfortable with the way sustainability was being discussed.Of course, reducing environmental impact is important. However, whether we install solar panels or reduce carbon emissions, we are often still talking about minimizing damage rather than creating positive change. I kept asking myself: even if we succeed in reducing harm, will the planet truly become healthier? What does the end goal actually look like?At the same time, environmental issues were increasingly being translated into numerical indicators and market mechanisms. Carbon trading, certifications, and sustainability metrics all had their place, but I often felt that the original purpose was being overshadowed by the pursuit of measurable targets. I found myself struggling to distinguish genuine ecological improvement from symbolic gestures.The answer came from Yakushima's natural environment.Nature does not argue through theories; it reveals its answers through outcomes. Where water flows well, life flourishes. Where circulation is blocked, vitality declines. The forest taught me that healthy ecosystems are built not on efficiency but on relationships and cycles.While participating in the restoration of degraded land on Yakushima, I began to see nature itself as the ultimate environmental textbook. Through direct observation, I realized that the most important question was not how to reduce environmental damage, but how to restore and strengthen the cycles of life.Sumu Yakushima emerged from this realization. It became my first attempt to explore whether architecture could move beyond minimizing harm and instead contribute to the regeneration of ecosystems. The project was born from a simple but profound question: can a building help life thrive?

What troubled me most about contemporary environmental discourse was its tendency to rely on a single metric.For example, when carbon reduction becomes the primary measure of success, we risk overlooking other consequences such as biodiversity loss, monoculture plantations, or large-scale deforestation associated with certain renewable energy developments. Nature does not operate through a single indicator, and neither should architecture.Forests, water, soil, plants, animals, fungi, and microorganisms exist within an interconnected system of relationships. When one element is isolated from the whole, we often lose sight of what truly creates ecological health.This is why I place great importance on the concept of the watershed.Rain falls on mountains, flows through forests and rivers, and eventually reaches the sea. Human settlements exist within that journey. Architecture is not separate from this system; it is part of it.For me, a building is not an isolated object. It participates in the movement of water, the health of soil, and the vitality of ecosystems. Its responsibility extends beyond its walls.What Sumu Yakushima proposes is not simply a low-impact building, but an architecture that actively participates in the cycles of life.If human beings are part of nature, then our homes should be capable of enriching nature as well. I believe this shift in perspective represents one of the most important challenges facing architecture today.

While observing Yakushima’s forests, I became fascinated by the immense network of fungi and microorganisms that exists beneath the ground. Healthy forests are supported not only by what we see above the surface, but also by invisible relationships within the soil.At the same time, Japan has a long tradition of using charcoal within landscapes and agricultural systems. Inspired by both ecological observation and traditional knowledge, we incorporated carbonized wood beneath the foundations and used charcoal-based materials throughout the project.Charcoal is highly porous. It retains moisture, air, and nutrients while providing habitat for countless microorganisms. Yet the charcoal itself was never the goal.What we were truly trying to create was an environment that could support biological activity and strengthen the living soil system beneath the building.The results were encouraging. Microbial diversity on the site was measured at levels exceeding those found in the surrounding untreated forest.For me, this finding suggests that architecture does not have to be a force of depletion. Human-made structures can potentially contribute to the enrichment of ecological systems rather than their degradation.I see this not as a construction technique, but as the beginning of a new design philosophy—one that reconnects architecture with soil ecology and recognizes that the health of a building site cannot be separated from the health of the living systems beneath it.

Around the world, we are witnessing accelerating biodiversity loss, deforestation, soil degradation, and the disruption of natural water cycles.In this context, architecture is often discussed as part of the problem. Buildings consume resources, alter landscapes, and contribute to environmental pressures. While this is true, I also believe architecture can become part of the solution.Although Sumu Yakushima was developed within the unique environment of Yakushima Island, its core principle is universal: understanding the ecological characteristics of a place and supporting their regeneration.I believe the role of architects will change significantly in the coming decades.Traditionally, architects have been responsible for designing buildings. In the future, I believe we will also be asked to design relationships—between water and land, between people and ecosystems, between communities and the natural processes that sustain them.The future of architecture is not simply about creating structures that blend into their surroundings. It is about creating places that contribute positively to the health of those surroundings.If Sumu Yakushima can offer any lesson beyond Yakushima itself, I hope it demonstrates that architecture can become a participant in ecological restoration rather than merely a consumer of ecological resources.

One of the greatest challenges during the development of Sumu Yakushima was implementing an approach that had very few contemporary precedents.However, it would be inaccurate to describe it as entirely new. Many of the strategies we employed—such as elevated floors, independent foundations, and respect for underground water movement—were inspired by traditional Japanese building knowledge that had existed for generations.The real challenge was that I was still learning.At the time, I did not yet have complete confidence in all of the answers. Could architecture truly support ecological regeneration? Could a building coexist with underground water systems and microbial networks? These were questions I was actively exploring myself.Whenever local craftspeople asked difficult questions, I often found myself reaching out to researchers, traditional builders, soil specialists, and practitioners from many different fields. Rather than visiting them, many generously came to Yakushima, walked the site with me, and shared their knowledge directly.What remains most memorable is not the difficulty itself, but the generosity I encountered.These experts spoke passionately about their fields of expertise, and I found myself constantly inspired by the new worlds they revealed. Each conversation opened another door. Each question led to another discovery.Of course, there was uncertainty and experimentation. Yet rather than feeling burdened by it, I remember that period as an exciting journey of continuous learning.Without the knowledge and support of those people, Sumu Yakushima would never have been realized.The experience taught me that regenerative design is not the product of a single architect's vision. It emerges when diverse forms of knowledge connect and collaborate, much like the living networks found within nature itself.

The Japanese word “Sumu” means “to live” or “to reside.” At the same time, it shares its pronunciation with another word, “sumu,” which means “to become clear” or “to become purified.”The name was chosen because it expresses a relationship that I believe modern society has largely forgotten.Since industrialization, human settlements have often been created by clearing forests, extracting resources, and importing energy from distant places. In many cases, the more we live somewhere, the more the surrounding environment is depleted.Yet I began to question whether this condition should be considered normal.For most of human history, people lived within the cycles of nature rather than outside them. Human habitation and ecological health were not necessarily in conflict.Today, I believe it is possible to rediscover that relationship without abandoning modern technology.At Sumu Yakushima, elevated floors and independent foundations help preserve underground water flows and ecological continuity. Carbonized wood and locally sourced materials support biological activity within the landscape. At the same time, solar energy systems, battery storage, and high-performance thermal design provide contemporary comfort and resilience.The goal is simple: to create a place where living and ecological clarity can coexist.A place where people live, and the environment becomes healthier.A place where a healthier environment, in turn, enriches human life.This reciprocal relationship is the philosophy embodied in the name Sumu.I do not see it as a radical idea. Rather, it is an attempt to remember something very old—that human beings are not separate from nature, but part of it.

People often ask whether Sumu Yakushima could only exist on Yakushima Island.Certainly, the specific techniques would differ elsewhere. A desert, a mountain forest, and an urban environment each require different responses. Regenerative architecture should never be reduced to a universal formula.However, what I believe is transferable is not the technique itself, but the way of thinking behind it.One of the most important concepts for me is the watershed.Wherever people live, rain falls, water moves across the land, and ecological systems develop around those flows. Human civilization has always evolved within watersheds.I view architecture as part of this larger living system.The role of a building is not simply to occupy land, but to participate in the movement of water, support healthy soil conditions, and contribute to the vitality of local ecosystems.The specific design solutions may vary from place to place, but the principle remains consistent.What matters is not the regeneration of buildings themselves, but the regeneration of the living cycles that already exist within a landscape.If we begin from that perspective, regenerative architecture can evolve into countless forms around the world while remaining rooted in the unique conditions of each place.

What I most hope people take away from Sumu Yakushima is a reconsideration of humanity's relationship with nature.For a long time, modern society has tended to frame human prosperity and environmental protection as opposing forces. We often speak as though we must choose between economic development and ecological responsibility, between human comfort and the well-being of the natural world.I do not believe this is the only possible future.Human beings are not separate from nature. We are participants within it.The goal of Sumu Yakushima was never to prioritize nature over people, nor people over nature. Instead, it was to explore whether both could thrive together.In that sense, the project is not simply an architectural proposal. It is a question.Can we create places where human well-being contributes to ecological well-being, and where ecological health enriches human life in return?I believe this question will become increasingly important as we confront the environmental challenges of the coming century.If there is one aspect of the project that has not yet received sufficient attention, it may be the idea that architecture should be evaluated not only through the experience of its human occupants, but also through its impact on the living systems around it.Comfort, beauty, and functionality remain important. But perhaps we should also ask whether a building contributes to healthier soil, cleaner water, richer biodiversity, and stronger ecological relationships.To me, that is one of the most exciting possibilities for the future of design.

When we confirmed measurable electrical activity connecting trees on opposite sides of the building site, I felt a profound sense of wonder.Of course, those networks already existed within the forest. We did not create them.What mattered was the possibility that the building had not interrupted them.Throughout the project, we tried to avoid treating the site as an empty canvas. Instead, we viewed it as a living system that already possessed its own relationships, flows, and intelligence.This perspective influenced many design decisions, including the use of elevated floors and independent foundations that help preserve underground water movement, airflow, and ecological continuity.The evidence suggesting that biological communication may have remained active beneath the building was deeply meaningful to me.It reinforced an idea that had been developing throughout the project: architecture is not simply the arrangement of materials in space.Architecture is also the design of relationships.Relationships between people and place.Relationships between water, soil, plants, and microorganisms.Relationships between human activity and the larger living systems that support it.The experience strengthened my belief that buildings do not need to dominate nature in order to be successful. They can instead support the conditions that allow life to flourish.

I have never wanted architecture itself to be the protagonist.At Sumu Yakushima, many of the architectural elements were intentionally simplified so that the surrounding landscape—the forests, mountains, sky, and sea—could become the true focus.The building acts as a frame through which nature can be experienced more clearly.At the same time, the project integrates contemporary technologies such as solar power generation, battery storage systems, high-performance insulation, airtight construction, and radiant heating and cooling.Some people see a contradiction between advanced technology and a close relationship with nature. I do not.In fact, I believe the opposite is true.The more secure and comfortable people feel, the more open they become to experiencing the natural world around them.If you are worried that a storm might break your windows, it is difficult to appreciate the beauty of the wind, the rain, and the forest. But when you feel protected, you can observe those forces with curiosity and wonder.Likewise, when a warm and comfortable interior exists, people are often more willing to step outside onto a deck, feel the changing weather, and engage with the landscape.Human beings explore because they feel safe enough to do so.The use of local cedar, regional soil, and other place-based materials further strengthens this connection. The building becomes part of the landscape rather than an object imposed upon it.Ultimately, I believe that people become healthier when the environment around them becomes healthier.And I believe that the environment can become healthier through the way we choose to live.This idea is reflected in the name Sumu itself.A place where people live, and nature becomes clearer.A place where nature becomes healthier, and human life becomes richer.If visitors leave Sumu Yakushima with a renewed sense that they are not separate from nature, but part of its ongoing cycles, then I would consider the project a success.Because perhaps the most important form of sustainability is not a technology or a metric, but the feeling of belonging once again to the living world.