While contemplating the act of suicide, second year high school student Akihito Kanbara notices the freshman, Mirai Kuriyama about to jump off of the school roof and instinctively goes to save her. Annoyed by his attempt to stop her, Mirai impales Akihito through the heart with a carmine sword. Some time later, Akihito and his friend Mitsuki Nase work on preparing an anthology for their Literary Club when Mirai disturbs them. It is revealed that Mirai had been stalking Akihito all week in an attempt to kill him. However Akihito outlines her futile attempts due to his immortality as a half-youmu. Afterwards, Mitsuki teases Akihito on being stalked by Mirai and advises him to steer clear of the latter. When confronted by Mirai after school once more, Akihito learns that that the Kuriyama clan was wiped out because of their powerful ability to create weapons from their own blood, leaving the former as the lone survivor. Afterwards, Mirai chases Akihito into a classroom when they are suddenly interrupted by a youmu crashing through the window, although famous Spirit World Warrior—Shizuku Ninomiya quickly deals with it. Akihito later treats Mirai to dinner and learns that she had been merely using him as battle practice before being left with an unanswered question. Meanwhile, Shizuku kills the previous youmu and extracts a stone at its core. The next day, Mitsuki once again warns Akihito to avoid Mirai, but he instead chooses to talk with the latter after school. While having dinner at the playground, Akihito learns that a youmu had been haunting Mirai's home, in addition to her hate towards her cursed ability as well as the act of killing. Empathizing with her, Akihito decides to help Mirai kill the youmu and both confront it at her home.