The site faces not only a wide street with heavy traffic but also a subway station. Adopting an RC structure, columns and beams might become too obstructive in a small room whose area is 30 square meters or more. However, the architects decided that if the spaces between columns and beams could be considered as niches, it would provide cozy rooms that protect the inhabitants from noise and vibrations. The sizes of the structural beams become smaller toward the upper floors in order to reduce the drawing force during an earthquake. This reduction of structural members varies the depth of the niches inversely proportionally compared to the distance from the ground. The dimensions are slightly adjusted so that they could be used as benches, low tables, bed spaces, and tables.