Yakuza tattoos
It's usual within yakuza circuits to tattoo themselves, usually is it their clan's badge that they tattoo all over their body.
The origin to why the yakuza tattooed himself comes from Bakuto. They usually tattooed in a black ring around the arm for each crime they committed.
Finally it became an evidence of strength, when it could take over 100 hours to do a backtattoo.The tattoo was to illustrate you were unwilling to accommodate yourself to societies rules and norms.
Now it is to illustrate your clanbelonging.