Koishi takes an interest in sex after reading a strange book in the scarlet devil library, eventually leading to her regaining conscious thought (since she apparently likes thinking about perverted stuff). She sets out to make a harem, but soon realizes the heavy burden that comes with her new-found emotions, thoughts and powers. Will her heart break under the pressure of reality?

A human eating Yōkai meets one human she doesn't want to eat. Such an ill-fated romance cannot be realized, yet it will happen. Will the Yōkai's mind break under the weight of her sins, especially now that acts similar to her own occur? You, the reader, shall look at what must be hidden. Find the truth before it's revealed, or you shall collapse under the sin of ignorance.

Ahri sets up a sexy trap for Sona, but things don't go the way she originally planned...