Gargoyle Supremacy - Chapter 44: I Go on a Date with a Grim Reaper

The doomsday fell upon the earth when a dragon coffin sealed under a snow mountain for ages shifted, and the civilization of gods and devils began. The whole universe turned into a fantastic new world where everyone could rise to the top through cultivation. A lucky young boy seized the opportunity, and started his journey to be an overlord in cultivation.

- Description from Novelupdates

Lucien, a guy who has nothing but the desire to save his mother. To get strong enough, he makes a contract with the demon of L.u.s.t. And now, only by making a great harem, will he gain the power to protect those dear to him.

Junpei Takeda, a high school student, is childhood friends with Noriko Tatsumiya and is bullied by Kido Shouta. One day, while bullying Junpei, they (Junpei, Tatsumiya, & Shouta) were suddenly summoned to a different world by the whim of “God”. Summoned Heroes with cheats, or so he thought. But it turns out Junpei’s stats were even worse than an average farmer. Tricked into a deathly labyrinth by the only one he trust, he walks the journey for revenge.

There are a total of seven sins, and a revelation is made to a young man named Alex that he is destined to become a demon lord, more especially a demon lord of sin called LUST.

It's not like he can change that and because he always knew something about himself was different—not in a physical sense, well, maybe a little—and not in a mental sense—but rather because he is thrown into a demonic war that compels him to accept his new reality.

He was only aware of a difference in himself. Relating to him and the ladies who are drawn to him... Well, it was more or less like he was a magnet in front of all the girls, and all the girls were drawn to him like a metal.