Another Lonely Hitman.

After serving ten years due to a drug-induced assassination of a rival gang boss, Tachibana enters a world that's nothing like it was when he went in. Once a respected and feared Yakuza mastermind, he now must try and adapt within the confines of the new generations vision of honor. As he still garners a somewhat decent amount of respect he just tries to get by. Hooking up with a prostitute he's been in passing by with he begins to feel some sense of comfort. Upon stumbling across her being beaten down by her pimp, Tachibana can't just sit by and do nothing. So he commences in putting down an old school Yakuza ass whipping, thus beginning a showdown with the 'now' boss, Sato.