Akihito Kanbara is a high school sophomore in the literature club who believes himself to be a "Meganest", and although he appears to be human, he is actually half Yōmu, which makes him invulnerable to wounds, due to the fact that he can heal so quickly, and also immortal. One day, Akihito meets freshman Mirai Kuriyama when it appears as if she is about to attempt suicide by jumping off of the school rooftop. Mirai is isolated because of her ability to manipulate blood, which is considered heresy even among other members of the underworld, so she is shunned. Soon after Akihito saves Mirai, disturbing events begin to arise.
Two years ago, Shibuya was ravaged by a biological terrorist attack using the deadly Ua virus. Maria Osawa was saved when her father inoculated her against the virus, but is left with partial amnesia from the shock. She works as a cameraman when she reunites with a girl named Canaan in Shanghai, China. A gifted assassin with synesthesia, she is under orders from an unknown organization for a yet unspecified mission.
Asahioka Branch School, a combined elementary and middle school in an isolated village, has only five students total, four girls and one boy. The girls are best friends, and pass the season with traditional activities like harvesting mountain herbs and fishing.
Kazuya Maeda is a high school student who has received a digital camera from his father. Motivated by this new hobby, he enters the school´s photography club. This gives him the opportunity to see several new perspectives towards the girls near him.
Chihiro Furuya, who loves zombies above all else, meets the sweet girl Rea Sanka by chance, and he ropes her into "resurrecting" his dead cat. But then Rea claims she actually has become a zombie, and asks him to take responsibility for it.