The story is set on a high school that the student council president Satsuki Kiryuuin rules by force. Wielding a giant Basami scissors sword, the wandering transfer student Ryuuko Matoi brings about upheaval on the campus. Ryuuko searches for the mysterious figure who caused her father's death, but confronting her are the student council's "four divine kings." Fortunately, Ryuuko is aided by a talking sailor uniform who tells her, "Wear me. When I am worn by you, this power will become manifest."