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.

(Source: Kinnikuman Wiki)