A 12-year-old boy named Naota is hanging out with 17-year-old Mamimi, the girlfriend of Naota's absentee brother. Their relationship is an uneasy one, since Mamimi seems to enjoy teasing Naota quite a bit. Suddenly, their time together is interrupted by the arrival of Haruhara Haruko, a seemingly insane girl on a motor scooter. She runs over Naota and then whacks him in the head with her guitar...