Ryuuko Matoi carries a large weapon shaped like half of a pair of scissors. She's looking for the woman with the other half, who killed her father. Satsuki Kiryuuin, student council president of Honnouji Academy, is said to know the woman's identity, so Ryuuko transfers there. Those who arrive at the school receive a special "reverse uniform," and Satsuki has used that power to rule the school in fear.