actually basketball it quite popular in Japan. at the university i studied at in Kyoto/Shiga (studied at two campuses) there were clubs and many circles (not so serious) for playing basketball. in Japan at least from what i could gather from playing it and from my friends, it is an indoor only sport. there didn't seem to be anywhere to play outside. besides a pair of sports shoes is to be used only inside or outside. not both.
Japan Basketball League:
JBL
basketball is reasonably developed there, but there are other sports that take more of an interest for most sporting fans. like in australia, basketball will always be a low level sport because there are too many other popular sports, including the indigenous Australian Rules Football.