When all the men in her small town turn into zombies and begin to attack the women, Japanese schoolgirl Sakura (Higarino) finds her life turned upside down. The trauma of witnessing the mass murder of her female friends and family members pushes her toward madness. Having few skills and armed only with her English textbook and a kyūdō bow, she sets out to survive. Having visions of a red-headed boy named Billy (Max MacKenzie), a character from one of her books, drives her toward insanity and she begins to lose her grip on reality. She wanders about, narrowly escaping her own death, until she finds Aoi (Mai Tsujimoto), a woman who is both equipped and mentally ready to kill. But this woman is dangerous and, rather than support, offers violence and more punishment. Seeking the real-life version of Billy, Sakura must decide whether to survive and find the answers or give up and die