Debuff Master - Chapter 59

What happens when a fanfic author with a habit of lying and scheming suddenly finds himself as a self insert during Duelist Kingdom? What happens when you have Yugi, Joey, Kaiba, and the rest encounter someone who knows all about every major player in their saga... and sees no problem with abusing said knowledge? Chaos, dear reader. Sweet, sweet chaos

As a promise, he went out into the world as an assassin. 3 years later, after becoming the Supreme Assassin, he gave up on everything he had and returned to the ranks of ordinary people. But one day, Kismet, a mystical game created by the National Research and Development had appeared.

Enigmatic hands, spectral frame, and one cunning strike just like the swing of the Grim Reaper. The Supreme Assassin takes on the mystical world, and how his legendary tales sets off, progressively ascending the altar to becoming the best.

- Description from Novelupdates

[Shelter System successfully bound to host!][Option One: City of Light, save the survivors in the apocalypse and become a glorious and benevolent savior.][Option Two: City of Darkness, humans who enter the City of Darkness can only become your slaves. And you, will be the devil ruling over the apocalypse.]Sorry, I am no saint, I choose City of Darkness! From today onwards, I will be a villain!