A combination of Miike's Yakuza cinema and Robocop. It's certainly a fun take on the more serious Yakuza cinema, and it allows Miike to go wild with some of his wackier impulses. The budget isn't really there though, so you have to be able to forgive the film some cheesier/less refined moments.
When a Yakuza goon is gunned down, a mad professor finds his body and uses it for his experiments. He brings the man back to life, transformed as an almost invincible cyborg. Remembering the people who killed him and his boss, the reborn Yakuza plans his sweet revenge and sets out to kill some people.
If you like fun Miike, you're going to love this film. He doesn't really go full-out, but the mix of action, crime and signature Miike weirdness is just extremely pleasant and so very easy to stomach. The film isn't too long, there are plenty of memorable moments and the performances are solid. Just look past the shoddier effects, and you're sure to have a blast with this one.