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.

"Jeff wants to be a good wrestler, but will his bad temper get in the way?"--Unedited summary from book.