Attacker You! chronicles the determined and spirited 13‑year‑old junior high student You Hazuki—known in Western dubs as "Mila," "Jeanne" or "Juana"—who relocates from Osaka to Tokyo to live with her father Toshihiko, a cameraman who has just returned from Peru. Her mother vanished when You was very young, leaving the family to navigate life together. Alongside her father resides You"s younger brother Sunny, who is fiercely devoted to his sister and follows her everywhere, from school corridors to volleyball courts. You also finds herself intrigued by Kyushi Tajima, the attractive blonde woman who appears on television covering volleyball matches, and puzzled as to why her father reacts so harshly whenever You mentions her.
You harbors a deep passion for volleyball and aspires to one day join Japan"s national women"s team at the 1988 Seoul Olympics. She joins her school"s girls" volleyball squad and quickly rises to become a leading player, despite the harsh coaching style of her homeroom teacher—who also serves as coach—and who physically reprimands players when they fall short of his expectations. A complicated friendship develops between You and former school champion Nami Hayase (French‑dubbed "Peggy"), a rivalry that culminates when both girls sign with rival professional teams. You also falls for So Takiki, the captain of the Hikawa boys" team (known in Western versions as "Shiro," "Serge" or "Sergio"), and pours just as much energy into courting him as she does into her sport.