Hanamichi Sakuragi, a tall, boisterous teenager with flame-red hair and physical strength beyond his years, is eager to put an end to his rejection streak of 50 and finally score a girlfriend as he begins his first year of Shohoku High. However, his reputation for delinquency and destructiveness precedes him, and most of his fellow students subsequently avoid him like the plague. As his first day of school ends, he is left with two strong thoughts: "I hate basketball" and "I need a girlfriend."

Haruko Akagi, ignorant of Hanamichi's history of misbehavior, notices his immense height and unwittingly approaches him, asking whether or not he likes basketball. Overcome by the fact that a girl is speaking to him, the red-haired giant blurts out a yes despite his true feelings. At the gym, Haruko asks if he can do a slam dunk. Though a complete novice, Hanamachi palms the ball and makes the leap...but overshoots, slamming his head into the backboard. Amazed by his near-inhuman physical abilities, Haruko quickly notifies the school's basketball captain of his feat. With this, Hanamichi is unexpectedly thrust into a world of competition for a girl he barely knows, but he soon discovers that there is perhaps more to basketball than he once thought.