The site of the house is located in the end of a narrow lane in a dense residential area. It is surrounded by retaining walls of adjacent plots which are raised on the north and east side. The house was designed for a young couple and their child on such a sunken site.The structure of the house is reinforced concrete on the ground floor and wooden structure on the first floor. Volume of the house is automatically decided by building bylaws such as FSI for floor area of the house and height restriction for the height of the house. That volume is placed unintentionally in the centre of the site, which resulted to create two open spaces on the east and west side. The east open space is a courtyard which is surrounded by retaining walls, and is closed space like inside of a house. A big opening is designed towards the east courtyard to have visual continuity between inside activities and outside activities. On the other hand, the west open space connects the entrance hall and garden of adjacent plots and a narrow lane. Doma, which is inside outside in-between space, is designed in the entrance area to enhance the connection between inside of the house and the west open space. Brown color metal sheets, which is very common material, is chosen for the external wall of the house to reduce the visual appearance from surrounding cityscape.Each floor is designed as open plan with a staircase in the middle. Living-dining room and kitchen are located on the ground floor, and a bedroom, bathroom and inner terrace on the first floor. The inner terrace on the first floor is a space for plants and a drying space for clothes and therefore is waterproofed. It is not to worry about getting wet on the floor when you water the plants.The house has many light wells which are randomly planed. The light wells have the same size and same square tube shape, and are also structure to support a roof. On the ground floor, each light well which has different angles, flames the sky randomly along with different positions. Inside of each light well is filled up with different quality of light depending on angles of light wells towards sunlight. The light wells penetrate through the first floor. It is also to make residents think usage of the space and activity. The position and angle of the light wells can be references for residents to create their own space by placing furniture in accordance with feelings and occasions.To understand the space of the house, I thought of a space in a forest and a space in a grass land. There are many trees in a forest. And when people are in a forest, trees will become clues or reference points to create activities. Play of children for instance, they will run in zigzag along with trees, turn direction at the point of a tree, or hide themselves behind trees, which means trees are creating rule of a play. A grass land on the other hand, children will be able to run at full speed or to play in a large circle and in a small circle without any obstacles. In this case, vastness is creating a rule of a play. In this small house, I thought that light wells which may be thought obstacles in one point of view, become like trees in a forest to create an unexpected flexible and free space. And I wished that it would give the residents the joy of life.