Agu runs out of the medicine he keeps to prevent his demonization, so he goes to the forest where there are dangerous monsters in search of ingredients for medicine.

When Agu is careless in the forest, he is attacked by something.
When he wakes up, he comes face-to-face with a mysterious monster, but it seems strange enough to be called "dangerous.''

The monster that looks inside the unconscious Agu's head transforms into something that looks exactly like Ria, his childhood friend.