Located in the ancient japanese city of Kyoto, the O house by Hideyuki Nakayama architecture is a kind of lean-to structure extending from a main 2-storey house.

O house takes its name from its form in which a kitchen, dining room, furniture and bath area, encircle the main house. These spaces are produced by spanning rafters located between the retaining walls of the adjacent and main house.

The o house space is somewhat like a passage garden. Inside is a curved horizontal space, where a portion of the staircase, thin steelframe floor and equally lined fittings are found. The gable side of the house shows its dollhouse conditions, which are open and visible from the adjacent street. Going back and forth everyday through this passage-like area, the residents can see the shape of the main house from outside at various angles.

The house itself appears like a tower, depending on where one views it. The place where the family sleeps is on the second floor of the main house, and one can access it from the staircase thatreaches out from the passage garden.