Sonya may look like a regular school girl, but in truth she’s a deadly assassin who keeps to herself. Despite many warnings not to get involved with her, ditzy Yasuna decides that she is her friend, even if it means getting her arm broken or ending up in a headlock each time she surprises the young hitman. And just to make matters worse, ninja girl, Agiri - an associate of Sonya's - also attends the same school. With Sonya resorting to violence at every turn and Agiri parading her various "techniques" at every turn, Yasuna’s school life is about to get all the more hectic... that is, if she can manage to survive in one piece!