The games are about various yakuza/ex-yakuza just living their best lives basically. The main plot differs from game to game, but most of them are what I would call an "every game." It's got a little bit of everything; the majority of them are absolutely batshit insane side missions and mini games while the main game is a brawler/dialogue heavy RPG.

If you like video games and anime, this is a series for you because it's basically both at once and every game is both self-contained and enjoyable on its own, but also references past games a lot and has impeccable continuity.

This one with pirates I have a feeling is going to be a lot like Infinite Wealth with Kasuuga being either one of if not the main character. He has a super wild imagination; every time you get into combat in Infinite Wealth, everyone changes to some fantastical creature or hero. Like you get into a fight with some drunk business men and suddenly they're fire breathing zombies. It's great.