Kenshirou ni Yoroshiku

ケンシロウによろしく

The "love, revenge, and feel-good" story centers on a young man who swears revenge against the yakuza. He studies the art of the "assassination fist" with all his might, and becomes an adult. But this man who is a genius at his martial art form realizes his techniques cannot actually be used to kill anyone. (Source: ANN)