The hero of the story is Kappei Sakamoto, a high school student with amazing athletic abilities who joins the basketball team of Seirin High School and quickly becomes one of the most skilled players. Kappei has one unusual handicap for a basketball player - his height; he stands not even one meter tall. His Achilles' heel is female undergarments; he has a particular interest in white panties, and is even more enthusiastic about joining the basketball team when he discovers that the team's female coach, Coach Natsu, wears white panties (although his inventive attempts to sneak a peek at said panties usually result in a physical beatdown from the hot-tempered coach). Eventually, Kappei's athletic prowess extends beyond basketball, and he tries out for - and excels at - every sport the school offers.

In the first episode, Kappei meets and becomes enamored with Akane Aki, a sweet, pretty girl who is quite athletic herself (she later joins the school's ping-pong team) and signs on as assistant coach of Seirin's basketball team. Much to Kappei's delight, not only is Akane pretty, but she also wears white panties, and Kappei sets his sights on winning her heart. Kappei eventually moves in with Akane and her family after his parents (who are rarely around) leave for the United States. However, Kappei has an unusual rival for Akane's heart - Akane's dog, Seiichiro, who has often fantasized about marrying his owner and, resenting Kappei, immediately seeks to sabotage his relationship with Akane through various tricks. Seiichiro can also speak, although only Kappei can understand him.