This single-family house is planned on a 1000 sqm site in the Tokyo suburbs, positioned at the interface between urban structure and surrounding nature. To the east, neighboring houses articulate a metropolitan scale; to the west, a dense grove evokes the spatial depth of the natural world. Responding to these contrasting conditions, five room-volumes are carefully arranged, with gardens inserted between them to mediate a balance between openness and intimacy. At the center, a living-dining space is enclosed by the volumes. Above, a large beam spans across them, with vertical posts rising from it to support the roof and define a vertical void. This aperture introduces sky and light, generating openness, while the mass of the structure lends a sense of intimacy. The overall composition serves as a spatial device for redefining the relationship between inside and outside, architecture and environment, at the edge of city and forest.