The battalion commander of frogs, Pyonshichi, directs soldier frogs while riding on a puppy. He arrives at a swamp near "Ginza-no-yanagi" (Ginza Willow). Osode, Pyonshichi`s younger sister, is at the top of the willow. From the swamp, Namako the catfish sees the brother and sister through a periscope, goes on land, uproots the tree, and kidnaps Osode. Feeling sorry for her as she cries in a cage at the bottom of the swamp, the sun drops a towel with which it was wiping its tears. That towel becomes a willow, and when Namako is asleep a willow branch grows and pulls Osode out of the bottom of the swamp. Namako notices what happened and attacks the willow where the brother and sister are. Pyonshichi asks for help and a full force of frog soldiers arrive. Even so, they face a tough fight against Namako. Bombs dropped from an airplane turn into a caterpillar, and then a Bangalore torpedo. Three fearless frogs take it and ram themselves into Namako. They give three cheers on the dead body of Namako.
Source: Japanese Animated Film Classics