Archmagician and Deviant-X System.

When a meteor strikes this planet, it creates a crater that rises above the surface of the earth, tears the sky, and creates a tall, towering structure known as a dungeon.

They brought the monster known as Eden-Zero and other calamities to the earth at the same time. Monsters with hard armor that could withstand nuclear weapons and hot weapons, which predominated much of human civilization.

However, against those powerful monsters, these weapons were powerless to do any harm—that is, until the E-tell voice began to ring inside people's heads. A new race that appears shortly after the arrival of E-tell provides them with a source to help them level up and become stronger.

Bringing people into what came to be known as the "Trial-Eden Period," a new era of knowledge and wisdom, where humans started to prevail and gain back the cities that they had lost. Or at least that is how the historical record was written, but a student seated in the back row of the classroom did not think it was true.

It is the story of a guy named Yu Han and his weird system that appears to have disturbed his normal life, which he used to treasure before.
A system, which ask of him to deprave every boys of their dream girls, and gather all of those girls for himself and him alone.
Deviant-X System