Japan has a tricky relationship with gambling that every traveller should know...

https://www.play-bookmarks.win/gambling-in-japan-is-a-curious-mix-of-strict-laws-and-quirky-exceptions-while

Japan has a tricky relationship with gambling that every traveller should know about. While most forms are illegal, there are popular exceptions like pachinko parlours, horse racing, keirin cycling, and kyoutei boat racing where betting is allowed