Architectural studio AOIM has completed a striking three-story residence in Tokyo's Koishikawa district, featuring an innovative curved roof design that captures, reflects, and distributes natural daylight throughout the interior spaces. The unique residential project demonstrates how thoughtful architectural design can maximize natural lighting in dense urban environments while creating a warm, inviting living space.
The house sits on a long, narrow plot in central Tokyo, surrounded by factories, apartment buildings, and commercial structures that significantly limit access to natural light. With only two sources of openness available - the depth extending back from the street and the narrow strip of sky visible overhead - the architects faced the challenge of bringing sufficient daylight into the compact living space. The innovative solution came in the form of a semi-cylindrical roof that curves in an inverted arc, creating a smooth, flowing surface reminiscent of kamaboko, a traditional Japanese fish cake.
This distinctive roof design serves multiple functions beyond its aesthetic appeal. As sunlight moves across the sky throughout the day, the curved surface scatters direct rays into a gentle, even illumination that fills the interior spaces. The quality of light continuously changes in brightness and color depending on weather conditions outside, creating a dynamic living environment that connects residents to the natural rhythms of day and seasonal change. Morning meals are bathed in focused light that feels like a natural spotlight, while throughout the day, the interiors experience subtle variations in tone and intensity.
At the rear of the residence, where views to the outside present both opportunities and privacy concerns, AOIM incorporated an atrium and terrace that function as a transitional space between private domestic life and the bustling city beyond. This area doubles as an artist's studio or atelier, capturing glimpses of greenery from neighboring properties while providing access to an exterior staircase. The staircase itself serves as both a screen and an extension of the living space, offering partial shelter while encouraging residents to step outside and engage with their neighborhood community.
The terrace has been specifically designed for casual use, functioning much like an outdoor bench where residents can comfortably spend time. This approach reflects the architects' intention to create spaces that blur the boundaries between indoor and outdoor living, despite the constraints of the urban setting. The design encourages interaction with the surrounding community while maintaining appropriate privacy levels for the residents.
Despite its modest scale, the House in Koishikawa makes efficient use of space across its three floors. The building covers just 56.43 square meters of ground area but provides a total of 157.84 square meters of usable interior space. The reinforced concrete structure utilizes external insulation, allowing the interior walls to remain raw and unfinished, creating a distinctive aesthetic that celebrates the material's natural properties.
The exposed concrete surfaces retain a hand-formed quality that contrasts beautifully with the precision of the building's geometric design. Rather than applying topcoats or polishing treatments, the architects chose to leave the concrete in its natural state, where its inherent roughness becomes softened and warmed by the natural light filtering through the curved roof above. This material choice creates an interesting dialogue between the stark, industrial nature of raw concrete and the gentle, organic quality of the natural illumination, resulting in interior spaces that feel both modern and surprisingly welcoming.
