This is a good place to start -- spending good money to bring more good players to Japan to help elevate the competition and the intensity and quality of practice.
"The only way to produce an NBA-level player is to have NBA level players playing in your league at multiple positions," a hoop expert said in a 2011 interview. "The first real Japanese NBA player will probably be a guard, so you need to have as many high level point guards and shooting guards playing in the league, so the Japanese players can test themselves every time they step on the court."
Instead, the bj-league and JBL (NBL is the future name) have been cutting back, using mostly foreign talent at the post positions. And that's a big mistake. Foreign talented is also greatly needed at the backcourt and wing positions -- on every teams.
Zero Japanese are in the NBA, and the Japan national team has failed to qualify for the Olympics since 1976. Obviously, the system is broken. The above suggestion will take patience and money -- good investment -- to make it happen. But it's worth it, every penny will be money well spent.