House in Kosai by FujiwaraMuro Architects

Located in a quiet residential neighborhood in Kosai, Shizuoka Prefecture, House in Kosai is a 102-square-meter contemporary family home designed by FujiwaraMuro Architects. Conceived for a couple and their two children, this compact Japanese residence explores how small, interconnected spaces can create a dynamic and ever-evolving spatial experience.

Rather than designing a conventional “box,” the clients requested a pitched roof house: a form that evokes familiarity, warmth, and domestic character. They envisioned a home open toward the street, with a centrally located yet enclosed kitchen, and a layout that allows full circulation around the house. The result is a carefully orchestrated architectural composition defined by stacked volumes, shifting geometries, and subtle spatial gaps.

Spatial Strategy: Stacked Volumes and Layered Gaps

The architectural concept is driven by misalignment. Instead of aligning floors and walls in a straightforward manner, the architects stacked and shifted volumes between the first and second floors. These intentional offsets create:

• Dimensional depth within a small footprint
• Visual connections between rooms
• Gaps between volumes that introduce light and shadow
• A subtle sense of movement and anticipation

The dining room slightly protrudes from the main facade, reinforcing the idea of volumetric layering. Between the first and second floors, a deliberate gap enhances spatial tension and allows light to filter through transitional zones.

By wrapping these volumes with a unified roof and exterior skin, additional voids emerge, between rooms and roof, and between interior spaces and the facade. As residents move through the home, volumes appear and disappear, producing a flickering effect of visibility and concealment.

Light as a Dynamic Architectural Element

Natural light plays a crucial role in shaping the atmosphere of this Japanese house. The protruding walls and offset geometries catch daylight differently throughout the seasons and time of day. This creates:

• Changing shadow patterns
• Subtle gradations of brightness
• A sense of depth beyond physical dimensions

Even though each room is intentionally compact, carefully positioned apertures allow glimpses into adjacent spaces. The entire house can be perceived intuitively, even when it is not fully visible. This layered visibility strengthens family interaction while maintaining spatial individuality.

The underside of the pitched roof becomes an atmospheric surface. Light transitions across it throughout the day, creating a constantly evolving interior environment.

Functional Organization: Circulation and Family Connectivity

The layout prioritizes circulation and spatial continuity:

First Floor

• LDK (Living, Dining, Kitchen)
• Bathroom
• Workspace
• Double-height dining and living area

Second Floor

• Master bedroom
• Two children’s rooms

The double-height living and dining space anchors the home vertically, visually linking both levels. From the first floor, one can perceive the second-floor volumes, reinforcing the idea of openness within compact living. Meanwhile, upstairs rooms sense the shifting light beneath the roof, connecting occupants to the overall architectural form.

The central yet enclosed kitchen allows the family’s presence to be felt throughout the home without fully exposing the workspace, balancing privacy and togetherness.

Contemporary Japanese Residential Architecture

House in Kosai reflects key themes in contemporary Japanese residential design:

• Compact living solutions
• Spatial layering within small footprints
• Pitched roof reinterpretation
• Light-driven interior architecture
• Interconnected family-oriented layouts

By transforming misalignment into a design tool, FujiwaraMuro Architects demonstrate how architectural complexity can emerge from simple domestic requirements. The house avoids monotony and instead offers an ever-changing spatial experience, where perception shifts depending on movement, light, and time.

This project exemplifies how thoughtful design can redefine compact urban housing in Japan, turning a modest 102 m² footprint into a rich, multidimensional family home.

All photographs are works of  Toshiyuki Yano