MTL - The Paranoid Protagonist is Addicted To My Stickers - Chapter 13 locked door

He is the master of six kingdoms. As long as he wanted, his cavalry is ready to wipe off any country.

As a kind of punishment, the wings of a demon king were cut, and he eventually lost all of his power. To get back his power, he made a deal with the angel. He will go to the realm of humans to find a special girl with a special skill who is meant to be her queen. If the woman got pregnant, all of his sins would be forgiven, and he will regain all his powers. But he didn’t think that knowing her would be an adventure for him as the king of demons in the human realm.

15 years ago the world discovered magic as well as mythical beings (basically beings from various legends) in another dimension. Humankind learned to summon these dangerous mythical beings and use their power to great effect. Seven countries formed contracts with these “mythical beings” and gained their allegiance as a result. The mythical beings will choose their summoners on their 14th birthday and give them a stigma. Schools have been set up to train summoners and magical swordsman (basically bodyguards that give the summoners time to cast their spell) as a result.

15 years later after the finding of magic Kazuki Hayashizaki is chosen as a summoner and given a stigma to indicate that. This is surprising since males aren’t chosen as summoners due to their low amount of mana compared to females. As the first male to be a summoner Kazuki is under a lot of scrutiny by almost everyone.

To complicate matters his sister (who’s a magical swordsman) is against him going into summoner school to train there as a summoner. Because summoners and magical swordsman have a cat mouse thing going on where summoners look down on magical swordsman as inferior so his sister naturally is against him going there. She’ll stop him even if it means going to war.

Kazuki however is determined to thrive in summoner school and has already determined to give it his all. Even if he’s the lowest ranked student (ranked E) and his fellow students intend to demean him he’ll prove himself as the strongest summoner.

Lucille was a top student when she suddenly passed away due to a car accident she was transmigrated to the novel that she was reading before her tragic ends, and what's worse she was transmigrated in the body of the Villainess Acantha Solaris who will also die without receiving any love from everyone.