Japanese basketball is suffering from an identity crisis. Besides Yuta Tabuse, the average citizen cannot name a handful of other top-level Japanese players. Indeed, this is problem No. 1.
Making matters worse, the Japan Basketball Association, the sport's national governing body, remains woefully incompetent when it comes to assembling a men's national team that can seriously challenge for a spot in the Summer Olympics, having last qualified for the 1976 Montreal Games. This is another Grand Canyon-size issue.
In other words, the sport is irrelevant to most people in Japan.