Counterattack! The Underground Space Choujin (逆襲!宇宙かくれ超人, Gyakushuu! Uchuu Kakure Choujin) is the fourth theatrical film based on the anime series Kinnikuman. It was released in Japan on July 13, 1985 alongside Dr. Slump and Arale-chan: Hoyoyo! Dream Capital Mecha Police, Captain Tsubasa: Great Europe Play-Off, and Dengeki Sentai Changeman: Shuttle Base Showdown. It is set after the Dream Chojin Tag Arc.
It is the first film to feature the character Geronimo and the last film where Eiji Kanie supplies the voice of Ramenman. It is also the shortest film of the series. It is based on the Kinnikuman special chapter Robin Memo (ロビン･メモ).
- Hydra King (ハイドラキング)
- New Sunshine (ニューサンシャイン)
- New Black Hole (ニューブラックホール)
- New Black Rain (ニューブラックレイン)
- New Asuraman (ニューアシュラマン)
- Hydra Buton (ハイドラブートン)
- Hydra Gun (ハイドラガン)
- Hydra Sumo (ハイドラズモウ)
- Hydra Indy (ハイドラインディー)
- Ukon Jr. (ウコンＪｒ)
As the whole world watches the Chojin Rugby game on TV, the "Underground Space Emperor" Hydra King (ハイドラキング) has his Uchū Kakure Chōjin (宇宙かくれ超人, Underground Space Supermen) kidnap Robin Mask. Their aim is to lure out the Seigi Chojins and then attack them using the Robin Memo, which contains info on all of the Seigi Chojin's weaknesses. Watching on TV all over the world, Kinnikuman and the Seigi Chojins get together and head for Planet Hydra. When they arrive they discover that Robin Mask has been placed on a crucifix and a time bomb has been attached to his chest. The mountains on which they stand break apart and the Uchu Kakure Chojins attack. Though their weaknesses are being attacked, the Seigi Chojins fight on. They eventually overcome Hydra King's cowardly attacks and defeat him with their combination technique Miracle Friendship Hold ・ Chojin Southern Cross.
- Opening Theme
- Blazing Kinnikuman (炎のキン肉マン, Honoo no Kinnikuman) by Akira Kushida
- Closing Theme
- When Buffaloman arrives in the room with his weakness, his hands are flesh colored instead of red. It occurs again as the Seigi Choujins are leaving Rikishiman to fight Hydra Sumo.
- After the scene where Rikishiman throws salt at the Kakure Choujins, some of the salt on Hydra King is colored pink. This may have occurred because Hydra Būton, whose skin is pink, was right next to him at the time.
- Geronimo knows the name of his opponent, Hydra Indy, without the character ever being introduced or mentioned prior to their fight. However, this may have been done intentionally so the viewers would know the characters name.
- At one point during Kinnikuman's fight with Hydra King, the inside of Nachiguron's mouth is colored blue instead of red.