The answer is:
tatami
The Katsura plan is organized around a grid pattern determined by the modular dimensions of the tatami.
Tatami is widely known in China and Japan as a flooring material. Tatami mats are thick, these are woven straw mats that measure about one by two meters in size. When thinking about a traditional Japanese home, most people automatically think about tatami, the traditional straw mat that has served as flooring for many centuries.
