The current state of the law in Japan outlaws most forms of land based gambling and all forms of online gambling. 
Japan is one of few first world countries with no land casinos. In Japan ll forms of gambling is controlled by the state which is limited to horse racing and the lottery.
Lawmakers are reported to realize that there is a tax revenue opportunity going to waste.
Land based casino operators have long had an interest in Japan.
Macau it’s a example and have successfully boosted tax revenues through legalized online and land based gambling. Japan is experiencing an ongoing recession and a declining tourist industry so there is little surprise that they are looking to boost their tax coffers from gambling.