It is hard to imagine a more literal image of high density dwelling than this, the Tokyo Apartment–Sou Fujimoto’s latest building. A collective housing project requiring a number of dwellings to be packed onto a tight corner site in a low-rise suburban neighborhood of Tokyo, the result has all the innocence and audacity of a child’s answer to the problem of urban density: a pile of houses. Childish things normally do not survive long in an adult world, except perhaps in Japan. That such a scheme could not only be thought up, but then also argued for by the architect, accepted by the client, financed by the bank, approved by the council, and finally built and inhabited is testament not only to the force of Fujimoto’s imagination, but also the curious liberties afforded by the Japanese city.