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.

Takashi and four of his classmates, fourth-grade students, cannot succeed in doing a forward pullover around a horizontal bar. Their P.E. teacher warns them: they have one week to succeed; if they resign now, then, tomorrow, facing life difficulties, they will always run away and become bums.