A hungry cat gets a job hunting mice at a sumo training center (heya), but once the mice are gone he continues to stuff himself until he is too fat to chase the mice that have returned--so he decides to train with the sumo wrestlers, and SumoKitty becomes a scourge of mice and an inspiration to the wrestlers.

Ninth-grader Kyle has always been the heavyweight on his junior high school wrestling team, but when a new kid shows up he loses the challenge and finds himself relegated to the B-team--until a girl on the squad suggests he move down a weight class.