Attacker You! follows You Hazuki, an ambitious and energetic 13-year-old junior high schoolgirl (known as "Mila," "Jeanne" or "Juana" in various Western dubbed versions of the anime), who moves from Osaka to Tokyo to attend school and live with her father, Toshihiko. Toshihiko is a cameraman who has recently returned from Peru. You's mother is absent, having left when You was very young. Also residing with You and her father is her younger brother, Sunny, who is very attached to his older sister and tends to follow her everywhere, including to school and her volleyball matches. You is also curious about Kyushi Tajima, the attractive blonde woman she sees covering volleyball games on television, and about why her father becomes very angry whenever You mentions her. You is passionate about volleyball and dreams of joining Japan's national women's volleyball team for the 1988 Seoul Olympics. She joins her school's girls' volleyball team and quickly becomes one of the top players, although her coach (who also serves as her homeroom teacher) is brutal and literally slaps his players when they fail to meet his expectations. You begins a tumultuous friendship with Nami Hayase (French name: "Peggy"), a former school volleyball champion and former arch-rival, which reaches a climax when the two girls join opposing professional teams. She also develops a crush on So Takiki (known as "Shiro," "Serge" or "Sergio" in various Western versions), the captain of the Hikawa boys' volleyball team, and puts as much effort into trying to win his heart as she does into her game.