Think at Yakuza game like it was a crazy japanese drama and a crazy good one at that.
It has extremely charismatic characters both protagonist and villain side, a plot that seems to intertwine Kurosawa to The Godfather, fighting scenes coming straight from Bruce Lee Enter the Dragon, all with crazy situations echoing the japanese society like an episode of Welcome to NHK.

And when you think the game showed you all it has and you are already having tons of fun and you think you can't ask for more... it surprises you with even more content and gameplay mechanics.

In gameplay terms, it's a game that mostly lives of its ambientation where the player goes from mission to mission while exploring the city of the game. Kamurocho (inspired by the real Kabukicho in tokyo) is filled with typical japanese attractions, shops, restaurants and all sort of weirdos with personal stories that are mostly an excuse to explore the japanese culture of the late '80. Some of those will unlock minigames resembling those of GTA but defintly more of a japanese taste.
During the exploration and missions there will be fights resolving in a somewhat beat em up flavor, with combos and fighting styles unlocked while progressing in the game and spending money.
I don't want to spoil too much, I'll just say that while the gameplay might seems somewhat simplicistic (especially expecting something of a fighter game or GTA complexity) it still works greatly to the point to never feeling boring. There was never a moment I felt bored.

This is a gem of a game and I fervidly and emotionally reccomend.
And absolutely play this if you are even slightly interested in japan beside their anime "moe" side.