One Piece: Don't Worry, I'm a Doctor - Chapter 181: Purple Lightning

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.

The invincible strongman who roams through the city by day and night, a supreme soldier king that moves across the urban landscape.

Florentia was reincarnated as the illegitimate child of the richest family in the empire.

The well-known and recognized throughout the Stern continent, strong and mighty, as well as the unique Wizard of magic cures, the most outstanding genius of the whole continent, Jason got into the flow of time, back in the uncivilized era during the first failed experiment, 3000 years ago. This was the period when the magic healers didn’t exist. How will Jason apply his knowledge in this backward era, wherever he reach the peak of glory?

- Description from Novelupdates