The first theatrical film of the anime series Kinnikuman. After winning the 21st Choujin Olympics, Kinnikuman plans to build his own theme park. As his friends and celebrities arrive, the sky grows dark and with a flash of lightning Kinnikuman's championship belt is gone. He then sees that it has been taken by Octopus Dragon III, who challenges him to take it back. Kinnikuman tries but fails and Mari is kidnapped. Octopus Dragon gives Kinnikuman a time limit to save her before she is fed to the monster Gigasaurus and then returns to his home world of Planet Metro (メトロ星, Metoro-sei). Despite his injuries, Kinnikuman is determined to go and reclaim his belt and Mari. Luckily, Terryman, Ramenman, Robin Mask, Warsman, Brocken Jr., and Rikishiman arrive to lend him a hand.

When Bibimbap, the last daughter of the Horumon Clan falls in love with Kinnikuman during her mission to assassinate him, her father Horumon Yaki enlists the aide of Shishkeba Boo of the Barbecue Clan, promising him Bibimba's hand in marriage. Shishkeba Boo himself has joined forces with the "Dark Monarch" Black Emperor, who looks to destroy Kinnikuman.

While Kinnikuman is on vacation with Mari-san's kindergarten class at Easter Island, the young wheelchair-bound Kouichi-kun laments being with an idiot like Kinnikuman, preferring to instead be with his favorite Seigi Choujin Buffaloman. Meanwhile, the other Seigi Choujins are also vacationing at ancient landmarks.

As the whole world watches the Choujin Rugby game on TV, the "Underground Space Emperor" Hydra King has his Underground Space Supermen kidnap Robin Mask. Their aim is to lure out the Seigi Choujins and then attack them using the Robin Memo, which contains info on all of the Seigi Choujin's weaknesses. Watching on TV all over the world, Kinnikuman and the Seigi Choujins get together and head for Planet Hydra.

While performing in a movie at Toei Eigamura, Kinnikuman suddenly disappears. Somehow, he has been sent to Edo Period Japan. In Edo Japan, a villain called Shuten Doji is threatening to destroy the Earth if he is not given Princess Mari. Always willing to impress a pretty girl, Kinnikuman immediately vows to destroy Shuten Doji. Aware of Kinnikuman's situation, Terryman, Robin Mask, and the other Justice Chojins travel to Edo Japan too (via Kinkotsu-obaba's powers).

Terryman, Robin Mask, and the other Justice Choujins are participating in a tournament in New York. Suddenly, Akuma Shogun (not the same as the guy from the series) arrives and defeats all of the Justice Choujins and absorbs their power... all except Kinnikuman (who was late for the tournament because he was busy eating gyuudon). Now Kinnikuman must defeat Akuma Shogun, whom now posseses the combined strength of all the Justice Choujins.

Meat-kun has been kidnapped by Iron Mask. In order to save Meat-kun, the treasure of Inmora Island is needed. Furthermore, the treasure is hidden in the Seven Story Tower, which is guarded by the brutal Senshi Choujins. When Kinnikuman asks Terryman and the Seigi Choujins to help him, for some reason they all refuse. Alone, Kinnikuman heads to Inmora Island to fight the Senshi Chōjin and is overwhelmed by their great numbers.