Since Japanese architects apparently are clueless about building houses that hold warmth and using central heating, the Japanese have to use kotatsu to keep warm in winter. A kotatsu consists of a table (usually for kneeling, washitsu-style) surrounded by a large, thick blanket that reaches down to the floor, and a small heating unit fastened under the table. Thus, the space under the table is always warm. People sit or lie around the table and put their legs under it to keep warm. Sharing a kotatsu is one of the archetypical images of happy family life in Japan. Cats love kotatsu.