Share accomodation in Japan isn't common and most people live in a studio designed for single person. I lived in a tiny studio in Japan when I was a student and having sharemate in Sydney when I came to Australia was an interesting expereince. However, the demands for share accomodation is growing and Naruse Inokuma Architects used new concept and designed beautiful shared house. Building brandnew shared house is very rare in Japan. The building has 8 private rooms plus shared space and if you divided whole space by 8, only 23 square meter per person. How clever idea!