kamiya architects' residence–hotel hybrid traces sweeping arc through the japanese forest

THE CONE EMERGES FROM THE FORESTED SLOPES OF KARUIZAWA

Nestled in the forested hills of Karuizawa, Japan, The Cone by Kamiya Architects redefines the boundary between structure and nature through an inverted-conical roof that blends into its sloped terrain. Designed as a timeshare villa—straddling the line between a private residence and a boutique hotel—the project sits on a steep 3,000 sqm plot, responding to both topography and forest with fluidity. From above, the building presents as a sweeping arc that responds directly to the site. The gently curving plan mirrors the slope of the land, and the uniform, dark roof surface forms a powerful inverted conical shape, tapering inward toward a central point and culminating in a subtle protruding chimney.

images courtesy of Kamiya Architects

KAMIYA ARCHITECTS BALANCE ENGINEERING WITH ATMOSPHERE

Though legally a wooden structure, The Cone employs steel-reinforced beams to achieve a generous 15-by-12 meter span in the main living area, eliminating the need for bulky wooden columns. Instead, slim iron columns discreetly support the architecture, allowing for panoramic openings that blur the division between interior and landscape. By minimizing structural expression, Kamiya Architects emphasize spatial experience over tectonic display, allowing the architectural presence to feel quietly powerful.

Inside, the inverted cone becomes a luminous volume. The white-painted ceiling acts as a gentle reflector, amplifying daylight and diffusing indirect lighting at night. The result is a soft, ambient glow that enhances the cone’s concave geometry, creating an atmosphere that is both introspective and expansive. The Japanese architects use this reflective ceiling to transform the structure into a sensory landscape, where light and form heighten the emotional resonance of the space.

from above, the building presents as a sweeping arc

A CHOREOGRAPHY OF SPACE AND STONE

A curved central corridor arcs through the building like a hidden spine. Its full extent never immediately visible, the corridor evokes a sense of mystery. Radiating from it are variously scaled rooms that engage with the forest in different ways—sometimes framing, sometimes opening fully to the surrounding trees. At the heart of the communal living area sits a three-ton boulder, found in the nearby mountains and repurposed as a fireplace. This uncut, unshaped stone introduces an element of natural randomness that defies human authorship, grounding the otherwise controlled architecture.

the gently curving plan mirrors the slope of the land