It centers on a girl named Wakaba Himekawa, who is aware that she is growing up slower than other people, but otherwise lives a peaceful life. On the same day that she finally gets her first period, her childhood friend Takaya confesses that he loves her. While Wakaba had never felt that way for her friend before, she is still happy, if confused. As she is about to answer Takaya's confession, an alarm suddenly sounds, and a broadcast begins that will change her everyday life.

Attempting to shake off a nightmare from her childhood, Itoko was supposed to be married in the village of Migomori. There, she saw a doll that looked just like herself. Itoko wonders why this doll was made and what is the "mother of blue" the villagers speak of. Itoko feels herself being dragged into an abominable village tradition and another nightmare.

In this world exist three species: the beasts, the humans, and the hunters. Since ages beasts have been the prey of hunters, and humans the prey of beasts. The story follows a famous and powerful hunter nicknamed Little Red Riding Hood, whom the life will change the day he comes across a young beast werewolf girl...

The story of the "sweetie-horror" manga begins when an unnamed character without memories gets lost and arrives at a mansion. There he meets Charon, a naive girl who has a secret.