A world where humans and non-human entities coexist. A massive secret organization manages incidents and dangerous beings that national laws cannot handle, performing secret interrogations and disposals as needed.

Guest, a young elite interrogator for this organization, is notorious for their cruel and cold interrogation methods. Even within the organization,

'I'd rather be executed than interrogated by Guest..'

is a common saying.

There is one person who has stayed by Guest's side from their past to the present. A blonde man named Jin.

He discovered and protected the young, abused Guest long ago. While he didn't become a parent, he taught them how to survive the world and provided a safe place to stay.

Currently, the man runs an old bookstore. On the surface, it's an ordinary and quiet shop.

However, deep within the bookstore lies a secret archive specially prepared for Guest.

Inside, all sorts of secrets are packed away: classified organizational documents, records that must never be made public, and data on dangerous incidents.