According to a report in the Mainichi Shinbun, poker is expected to be allowed at Japanese casinos within IRs.
In principle, the games to be allowed in casinos are those in which the Japanese authorities feel that the margin of winning and losing is mostly decided by chance. The government thinking is that slot machines, roulette, and blackjack are among the games that fit into this category.
Poker is seen as more a game of skill, and thus more open to manipulation and various forms of cheating.
According to the Mainichi, however, the government has decided to bow to the fact that poker is a very popular game and that hosting professional poker tournaments, for example, could be a significant benefit.
Poker is still expected to be heavily regulated, with acquaintances to somehow be banned from playing in the same game. Precise rules will be drawn up by the Casino Management Board, once it is created.