Jason would've tried to live a normal life, after transmigrating into a strangely familiar alternate dimension, where Class and Levelling up was a thing, but soon he finds out he was a contractor of a Great Demon, who acclaims to make his life a miserable hell.

Jason, once an attorney at law, but now a Great Demon's advocate.

Through one magical event, his life changed. From living in a rundown apartment, he became heir to the fallen Great House of Locksmith. A minor character who was meant to die no matter what.

He would need all his wits, intelligence, courage, and some magical power in one place if he wants to keep his life. However, all hope was not lost, and coupling with the knowledge he was imparted through the game, he strives to do some good. Sadly, the the morality of the grim world is screwed. He has to twist his finger in schemes to do simple good.

Follow Ian as he adventures into the strangely familiar fantasy world—sometimes on the big stage while mostly on the background—attempting to save all the heroes as well as himself, but his quest becomes a lot harder when he is in cahoots with a demon.