Punch Rush JK Tara-chan

Overview

Katsuo Nikaido, a.k.a. "Fist King," is renowned as the strongest, undefeated delinquent in all of Japan. However, no one knows that behind the stories of his legendary battles, there is a girl behind the scene... Her name is Tabara Nikaido. She is the fighter who took her brother's name and fought in secret, and defeated all the men who stood in her way....... A slightly naughty story about a legendary fighter who happens to be a "tsuyokawa" JK! (Source: Comic Days, translated)

Source: AniList