There is an ancient prophecy shared amongst the kingdoms of Chikyu- 2,000 years after their fall, the Territorial Empire Bugnarok will once again rise up to kill all humans. However, five kings and their guardian deity, King-Ohger, will stand up to face them. This is the story of kings who will defend Chikyu, as well as a coming-of-age story for one young man who will achieve kingship henceforth.

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.