A former American G.I. joins a yakuza family after his release from prison in post-World War II Osaka.

The show focuses on a man named Kenji and his younger sister Yasuko, whose parents died in an accident 10 years earlier. Kenji was once the leader of a gang, but in order to support him and his sister, he began making a living as a shojo mangaka. His character normally wears glasses and appears to be a gentle guy, but he throws off his glasses and reverts to his violent side whenever he tries to protect Yasuko from danger. Part of the story follows Yasuko's romance with an intelligent and good-looking man named Jun Tsubaki. Jun's older sister Erika now runs a flower shop, but Erika was once a leader of a female gang, and she used to be in love with Kenji during those days.

Takeshi Hongo is a promising young man with a passion for motorcycle racing. However, his dreams are suddenly ruined when he gets kidnapped by Shocker, the evil secret organization planning to dominate the world. After being remodeled into a cyborg, Takeshi escapes and swears to protect the world from the inhuman monsters.