Gambling in Japan is a curious mix of strict laws and surprising exceptions....

https://uniform-wiki.win/index.php/How_to_Bet_on_Horse_Racing_in_Japan_as_a_Foreigner

Gambling in Japan is a curious mix of strict laws and surprising exceptions. While most betting is illegal, you’ll find popular legal outlets like pachinko parlours, horse racing, keirin cycling, and boat racing called kyoutei