Just speaking of genres and starting points: if you're looking at the series from the perspective of wanting a JRPG (and here I'm assuming you mean that you want something turn-based), then you'd want to start with Yakuza: Like a Dragon, which is the first turn-based game in the series and one that introduces a new protagonist. The sequel, Infinite Wealth, is the same style of game.
Pretty much any other Yakuza game you're going to see will be more action-focused and have real-time battles, but still with RPG elements. Yakuza 0 is a commonly-suggested starting point for the action-based entries or the series as a whole; it's a prequel but one that still works well as a place to start.
Pretty much any other Yakuza game you're going to see will be more action-focused and have real-time battles, but still with RPG elements. Yakuza 0 is a commonly-suggested starting point for the action-based entries or the series as a whole; it's a prequel but one that still works well as a place to start.