Kosuke Okano

Dr. Octo who researches octopodes decides to take over the world as he deems the eight legged creatures a more suitable master species than humans. To do this, he takes an idol singer Sumire Hoshino (aka Perman #3) hostage. Mitsuo Suwa (aka Perman #1) likes the idol dearly (as he doesn't know the real identity of his Perman partner) and becomes so angry that he transforms to go rescue her. But fighting a giant octopus is more challenging than it looks!

An origins and highlight film showing how Mitsuo met the alien that gave him the equipment to become a superhero (which for some reason was never explicitly shown in the two main anime, both just start with Mitsuo already having the powers), how he works together with the other Permans, and the rowdy fight with the antagonists.