Sega is releasing a companion app for Yakuza Zero for PlayStation Vita in Japan. This has an underground arena where you can give contenders a beat down to win prize money.
Players can also enter a gambling den with Kazuma Kiryu or visit a casino as Goro Majima to win money by playing blackjack or koi-koi. Money and items earned from the Yakuza Zero app can be transferred into the full game.