Ring ni Kakero (1977)

Takane Kiku and Takane Ryuji are the children of a legendary world contender boxer. Kiku, the daughter seems to have inherited her father’s boxing sense and tries to teach Ryuji to become a world contender. However, Ryuji hates boxing and gets picked on. After Kiku and Ryuji leave their hometown for Tokyo, Ryuji eventually learns to discover a passion for boxing after an encounter with a boxing prodigy, Kenzaki Jun. This will eventually lead him to learn crazy moves and out of thiw world opponents to become one of Japan’s top junior boxers.

Source: www.anisearch.com/manga/3756