Japanese high schooler, Sato Kugo, has been speaking to a voice in his head for as long as he can remember. When he's suddenly transported to another world, the voice stops.
Kugo becomes a certified investigator in this strange world, solving all sorts of cases. However, he's thrust into a mystery greater than he could have ever imagined, as he journeys to uncover the secrets of his past.
What is the mysterious voice? Why was Kugo brought to this world? Who even is Sato Kugo?