Yakuza Cleaner

"I’m Taiga Banjou, and I'm the new janitor at this school, starting today."

Taiga Banjou was raised by the Yakuza. An expert killer who has been part of the underworld for as long as he can remember. However, the Yakuza as an overwhelming presence is a thing of the past. Gokudou is now a relic, left behind by the times, and the Yamada-gumi, to which Taiga belonged, has been dissolved and reborn as a respectable company. The assassin has become a janitor. His workplace has gone from the underworld to a school. Now, fighting and violence are forbidden for a reputable employee, let alone murder. However, what awaits Taiga is a high school full of delinquents and filled with rampant bullying, violence, smoking, drinking, and all sorts of bad behavior. A situation that even the teachers and other adults can’t handle. “I’ve come to clean up this filthy school.” Making full use of the skills he mastered to survive in the underworld, the former yakuza’s “filth” clean-up job is about to begin!

(Source: Hyke Comic, translated)