The site is in the residential area in Tokyo. The site faces two private roads of south and west, the path in south side is the dead end. In this area, every road is surrounded by houses , a row of houses along the street turns each back on them. There is wall around the house or the house has only small windows usually to protect privacy of inhabitants. However, the client requested that “I don’t want that the daylight condition of the house becomes worse by shutting out the walker’s eye. It’s better to consider the use of the basement with privacy and enough daylight”. In addition, he requested the bright living room with high ceiling, and flat roof. Therefore, it was necessary to use the basement, considering the rigorous regulation of the elevation level in this site.

The basement is generally thought that sunlight is not come into so much. However, if the living room which needs light entirely is set in the basement, the upper-side is opened as the stairwell and the room gets enough ceiling level, the basement can be the brightest and comfortable. In the first floor, each entrance is set in front of each private road in south and west, and in result, the eye can pass through the entrance from each private road. By placing the living room in the basement, inside room can be more spacious in addition to protecting the privacy, and the upper side of that has the open space which the eye can pass through outside. The opend first floor which has the two entrances, serves as the middle floor, that is, the first floor is connected to the family zoon in the basement and the private zone in the upper floor directly. The entrance space is used as the gallery, in the visual effects the walker can look in.

The top light on the stairway and the sunlight from the day area pour into the living room in the basement, changing the angle and lightness by the season, time and the weather. It is in the basement that the inhabitant can feel the variation of the light. Looking up at the living, they can see the blue sky during the day time, the starry sky at night through the top light and glass on the dry area.