Baseball player Daisuke Ootaka attends Torioka University, the alma mater of his late grandfather, in order to honor the man's memory as well as continue to pursue his sport. He is surprised when he discovers that Torioka's players are average at best, their only merit lying in their overwhelming passion. What is more, the team's captain is the extremely short and extremely odd Suzume Morino—known simply as "Chun"—who does nothing but grate on Daisuke's nerves.

When it all grows too much for Daisuke to handle, he informs the captain of his wish to leave. In a shocking turn of events, however, Daisuke finds himself being blackmailed by Chun. Forced to stay on the team, Daisuke now has to deal with Chun constantly following him around and exhibiting infuriating behavior. It is clear that Chun is hiding secrets, which somehow involve ace baseball player Reiichi Shiratori, who is from the top-of-the-league team known as the Yokohama Stars.