Wandering Meteor - Chapter 27 Covalent Bond Strike

In a world where all magical spells have been captured into cards, those who can build a deck have the most power.The most Arthur could ever hope for was to someday earn a trash-tier spell card. When fate grants him a legendary Master of Skills card, he's thrust into a world of opportunity and danger.To survive and grow strong, Arthur must learn skills. All the skills.

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.

Childhood sweethearts.
The most popular person in school is my childhood sweetheart.

- Description from Novelupdates

A world where God will grant abilities called Skills to those who come of age. The protagonist, bestowed with two skills, uses them and rises to an existence called a hero.