This small guest house in resort area of Karuizawa represents Kuma’s unique approach to the architecture. The guest house supported mainly by two large columns and slender supporting 90φ slender columns supporting the cantilevered slab. We have planned that the elevated guest house will be lit warm 2800K while the lower level by cool 4200K. This differentiation of color temperature successfully expressed the floating floor in the middle of forest. A slender 90φ which solid steel columns supporting cantilevered slab were lit with special low-volt fixtures which can be fit into the slab. The living/dining/kitchen being one room was distinguished by switching and dimming the circuit. The Japanese traditional tea room was placed next to the living room created a surprised contrast. We are still designing garden lights which will be compatible to both serene tea ceremony and a dynamic view of forest from the living room. Both interior and exterior lighting demands a careful coordination and dialogue with the owner, architect and artists involved in the project.