Ami is a young, cute high school student, who is trying to escape her dark past. She is gregarious, looks after her younger brother alone (their parents are both deceased) and after school, practices her jump shot in the school gym. Unbeknownst to Ami, her brother is fodder for the the local school gang, led by the young punk heir to a Yakuza family. He is killed by the bullies, right in front of Ami. Something snaps... Ami becomes a killing "machine", seeking revenge on the class bullies. Unfortunately, she loses her arm during the fight, and the Yakuza punk leader narrowly escapes. However, Ami is soon retrofitted with a high powered machine gun for an arm and continues on her bloody path of vengeance!