Interviews are available in English only. Open the English page.
Interviews with Wataru Sato
Designer profileGrand Interview
15 June 2026 · Yoshinogawa Valley Ristrutturazione dell'edificio della sede centrale
When I first visited the building, what impressed me most was not the building itself, but the landscape of the Yoshino River stretching beyond it. In particular, I noticed that the river and the building were aligned along almost the same axis, and this observation became the starting point of the project.The Yoshino River and the surrounding valley are often referred to as the “mother river” of Tokushima Prefecture, having historically nurtured the region’s culture and industry. I wondered whether bringing the river’s axis of flow into the building as a linear void could generate new flows of people, culture, and activity within Kitaoka-group headquarters. To achieve this, we divided the building into two wings centered around the entrance and inserted a 50-meter-long linear void between them.We call this space the “Valley of Light.” By allowing light, wind, views, and human activity to pass through the building, we sought to bring the presence of the Yoshino River into the interior and transform it into a new organizing principle for the entire architecture.
In Japan, many anonymous existing buildings are replaced through a cycle of demolition and reconstruction. However, although this building was over forty years old, it had been built under post-1981 seismic regulations and its structural frame remained in excellent condition. We began the design process by asking a simple question: “Does it really need to be demolished?”Existing buildings accumulate layers of time, memory, and relationships with their communities—qualities that never appear on drawings. Rather than tearing the building down and starting over, we believed it was possible to create new value while preserving and activating those accumulated qualities.There are countless buildings of the same generation throughout Japan. Through this project, we wanted to propose the idea that such buildings are not only reusable, but can also be transformed into architecture with a level of originality that sometimes exceeds that of new construction.
Before improving mechanical systems, we first considered space itself as an environmental device.The central void and skylights bring natural daylight deep into the building, significantly reducing the need for artificial lighting during the day. At the same time, the vertical movement of air created by the void promotes natural ventilation and helps reduce cooling and heating loads.As a result, primary energy consumption was reduced by approximately 30 percent compared to the building before renovation. We believe environmental performance should not be something added afterward through equipment alone; it should emerge from the spatial composition itself. The form of architecture should generate environmental performance, and energy reduction should be a consequence of that design logic. This was the architectural approach we sought to realize.
The Yoshino River is more than a scenic landscape; it is an essential force that has supported the culture and industry of the region. Rather than imitating the physical form of the river, we sought to translate its behavior into architectural space.A river continuously gathers and carries people, goods, and information as it flows. Similarly, the central void was designed as a space that accommodates movement and interaction while connecting the entire building.For us, regional identity is not about applying local motifs or stylistic references. It is about understanding the forces, relationships, and dynamics inherent to a place and reconstructing them as a new architectural principle.
Excavating a 50-meter-long opening through the center of an existing building presented significant structural and fire-safety challenges.We repeatedly collaborated with structural engineers and contractors to verify the impact on the existing structure and ensure the safety of the large daylight openings. Throughout this process, the key was not to reject the existing building, but to intervene with a deep understanding of its characteristics and limitations.Ultimately, these constraints refined the design. They pushed us to uncover the latent potential of the existing structure while creating a completely new spatial experience.
The Benjamin tree was never intended as a decorative element.The central void is a place where not only light and wind, but also human activities intersect. By placing a tree at its center, we hoped to create a natural focal point that encourages people to gather, stay, and engage in conversation.Plants also grow and change over time. For us, the tree symbolizes an environment that continues to evolve through use, rather than a building that is considered complete at the moment of construction.
From the beginning, the team at Kitaokagumi had a clear vision of communicating new ways of working from a regional city to the wider world. Because of this, they strongly resonated with the idea of treating the office not merely as a workplace, but as a platform for experimenting with new forms of work and interaction.In regional areas of Japan, the relationship between family life and work tends to be closer than in large metropolitan cities. We sought to embrace this characteristic by proposing an environment where not only employees, but also their families and members of the local community could naturally engage with the space.Since completion, the building has hosted community events, welcomed visitors, and supported a variety of activities beyond conventional office functions. Seeing the architecture begin to operate as an interface connecting the company, the community, work, and everyday life has been one of the project’s most meaningful achievements.
Our practice is deeply interested in rediscovering and renewing existing value rather than simply creating something new.This award demonstrates that architecture does not need to begin from a blank slate. Even an anonymous prefabricated building in a regional city can become a source of new cultural value when its latent potential is carefully reinterpreted.We see this not merely as recognition of a single project, but as an acknowledgment of our broader design approach—one that focuses on editing, transforming, and reactivating what already exists.
Although working styles have changed dramatically in recent years, many offices still rely on desk-centered layouts.Through workplace research, observations of actual usage patterns, and interviews with employees, we came to believe that the key question is no longer where people work, but how they encounter one another.As a result, we designed an environment composed of diverse places to work and opportunities for spontaneous interaction rather than fixed seating arrangements. For us, flexibility is not simply a matter of layout freedom; it is a spatial strategy that supports organizational culture and collaboration.
We regard the existing building itself as a material, equal in importance to any new material introduced into the project.Throughout the design process, we carefully observed existing finishes, structural elements, and traces of past use, considering how they could be integrated with new interventions. Preserving existing elements was never about conserving the past for its own sake; it was a creative act aimed at generating new value.We believe that architecture is not only about creating value from nothing—from zero to one—but also about renewing value by reconnecting things that already exist. This project was an attempt to demonstrate the potential of that approach.
