Located in the forest of Karuizawa, this hall is the final building in a ten-year project developed with the client and contractor. The site includes dog-friendly facilities and expanded gradually over time. Serving as a lounge and indoor training space, the building opens on both sides to connect with the surrounding forest. Clerestory windows between three roof volumes bring in natural light, creating a sense of Japanese-style transparency. The architecture invites a quiet experience of nature through openness and form.