John is reincarnated into a world that knows all about Siders, a term used to describe people like him.

However, John is unlike the rest of the Siders and is reincarnated with an Idle System.

He gains more than anyone else when he kills, becoming an assassin to kill those that cross his bottom line.

He starts on the road of immortality thanks to the Idle System. As he gains strength, will he give in to the temptation for more power and start massacring innocents?

Will he become a Demon or a Saint in the eyes of the people?

What will John choose?

50 Chapters in the first volume, over 75,000 words.