Answer:
I don't know much about Japanese stuff (despite being Chinese). I do know, however, that Japan, especially during old times, used these materials since their land has abundance of this. Japan is mostly forest. Rice is also used due to, yet again, abundance. In Asia, they didn't know much crops except for rice, and Rice is also extremely easy to grow since all you have to do is overflood the field. This art of construction was also a reason why there were constant fires in the area.
