Mysteries aren't just secrets, they're objects! There is the Elixir of the Moon, which restores one's youth! The Songs of Another World, which must never be uttered aloud. The Curious Report of the Enchanted Land, which contains the testimonies of those who have been spirited away! And now, in Tokyo, these mysteries and more are reappearing in the form of urban legends.
Burnt-out novelist Ogawa Sumireko and demon boy Adashino Ren are out to collect as many as possible, but Sumireko has a knack for not just finding but triggering the magical effects of the mysteries! Will she survive her brush with the supernatural?! Does the demonic Ren have other plans for her?!