The entire Justice Choujin roster gets lured into a trap on an alien planet with their weaknesses on file. It's a premise that should have been the series finale, not a mid-run movie. What makes it work is pure escalation: every single fight matters because the roster is finite, and losing one Choujin actually costs something in a way the TV series never quite managed.

While the whole world watches a choujin rugby match on television, the Underground Space Emperor Hydra King sends his Underground Space Supermen to kidnap Robin Mask. His plan is to use the abduction to lure out the Justice Choujins, then strike at them with the Robin Memo, a record of every Justice Choujin's weaknesses. Kinnikuman and his fellow Justice Choujins see what has happened on the broadcast, band together, and set out for Planet Hydra. The result is a 1985 movie that blends action, comedy and sports.