When Ken's father successfully constructs a fully automated robot, Ken decides to take it for a spin with his pet cat, Mike.
In a totally nonsensical chain of events, the robot crash lands on the mysterious "Pologon Island" where Ken and Mike discover a strange rock that can float on water and swerve in mid-air.
After arriving home, Ken shows the stone to his father who immediately recognizes it to be nothing more than bird poop.
Soon after, Ken and his cat find themselves accosted by a group of hostile Kappa before having their bellybuttons stolen. The only way to recover their stolen navels is by beating the cunning Kappa in a game of baseball!
Ken soon rounds up a ridiculous bunch of players including a baby and a wooden doll and, with the help of his magical bird poop, sets about reclaiming his stolen bellybutton!
Written just 6 months into Shigeru Mizuki's career as a Manga artist, this is a highly unusual and much sought after comedy gem from the 1950's rental comic book era.