I am a high school student. This summer, I am visiting a small town in the country. The town is surrounded by mountains and people peacefully coexist with ayakashi (ghosts). I don't remember this place, but I feel like there was something I cherished there. The people I spend my time there all feel somehow important. They are Giou (an ayakashi), Shinonome, Shu, Takatora, and Chihaya. I get involved in a trouble due to appearance of an another mysterious ayakashi. Mysterious phenomena... Nightmare... I don't wanna remember that thing, but I have to... When the moon becomes full, what will happen to me...? Now, my summer starts...