Cat House is a minimalist interior design located in Tokyo, Japan, designed by Seiji Iwama Architects. It is a renovation project of a nearly 30 years old building. The architects transitioned the building into its skeletal structure and changed the living room which was located on the first floor to the second floor. In urban areas of Japan, homes mostly exist under dense conditions. Therefore, the first floor is affected by the shade of surrounding buildings, and as a result, the living room was arranged on the second floor to create a sunny and comfortable environment.