Attacker You! is the story of ambitious and energetic 13-year-old junior high schoolgirl You Hazuki (variously known as "Mila," "Jeanne" or "Juana" in Western dubbed versions of the anime), who moves to Tokyo from Osaka to live with her father Toshihiko, a cameraman recently returned from Peru, and attend school. You's mother is not in the picture, having left when You was very young. Also living with You and her father is her younger brother Sunny, who is very attached to his older sister and tends to follow her everywhere she goes, including to school and to her volleyball matches. You is also curious about Kyushi Tajima, the pretty blonde woman whom she sees covering volleyball games on television, and about why her father becomes very angry whenever You mentions her.