There are no weight classifications in professional sumo. It's a brutal sport in which only the strongest survive, and anybody ready to put their skills to the test can enter the ring. However, there is a minimum size requirement to be a professional sumo wrestler, and despite his incredible talent and hard effort, young Hinomaru Ushio does not satisfy that criterion. Hinoshita Kaisan, a tiny youngster with lofty ambitions, aspires to the top level of sumo. He can only become pro if he becomes the High School Yokozuna, a title awarded to the strongest wrestler in high school contests. Ushio is under a lot of strain and has a limited amount of time. If he is unable to demonstrate his abilities in high school competitions, he may lose his chance to go pro permanently, and the odds are stacked against him.