As Ryoko Mitsurugi goes to Daimon High School, she gets confronted by a group of ninjas and fends them off easily in a K-Fight, an officially sanctioned duel to settle disputes between folks at the school. Later on, when she prepares for a tournament where the winning club gets 100 times their usual funding, Ryoko finds a pendant necklace in a locker and puts it on. She faces her rival kendo senpai Azumi Kiribayashi in a duel but strange things begin to happen soon afterwards.