It is a Garden stands in the forest of Karuizawa, surrounding and surrounded by the trees and plants of the forest. The house was designed as a guest house containing a private art gallery for the owner’s collection. Its shape, being flat and square, has a floor plan entirely defined by five courtyards alone. All facades of the building are made of concrete walls and black glass, clearly dividing its interior space from the external environment. The house opens its reinforced concrete roof to the sky in order to create five courtyards. The exterior roofs tilt inwards only vertically inviting light as well as shadows and reflections of the surrounding nature. The interior roofs and floor levels consequently create rhythmical geometry to support the simplicity of the exterior. All rooms are designed to face the courtyards each of which is distinct in character designed to receive light at different times of the day. The sun rises and sets. The moon waxes and wanes. This unbroken rhythm of light, to which we submit the entire architecture, defines this house.