Emiko Koizumi, a fifteen-year-old high school student in Tokyo, is convinced that her life was cursed to forever and always remain uninteresting and repetitious. Every day, Emiko goes through the same old routine---wake up, go to school, study, come home, sleep. But, one day, everything changes and her butterfly charm necklace miraculously transforms into a katana used for slaying evil monsters. It's ridiculous but after her "biology teacher" tries to rip her throat open, Emiko has no choice but to accept the truth and use the swordsmanship skills she learned from binge-watching the Naruto series to protect earth from being ruled by darkness. I mean, how hard can it be?