Being 100% genuine, Y4 is probably the best entry point in the series. It's the most... "Yakuza" game in the series if that makes sense. It's got some of the best combat in the series, a banger OST, solid substories, and has some of the biggest ups and downs for a story in the series (rubber bullets isn't a bad twist, everything else in the finale does though). You don't need the knowledge from past games to enjoy the game more like you do 0 or K1, it doesn't have an unrefined combat system like 1 and 6, it's fun the whole way through unlike several other games in the series. Y4's (and the other PS3 games) are severely underrated and super fun