Mushoku Tensei - Volume 9 Chapter 2 — Guardian Magician Introduction - Fitts

A series of short stories in the world of Toaru Majutsu no Index organized into chapters featuring Kanzaki Kaori as the protagonist, going around the world and space doing missions for the Church of Necessary Evil, however, there is more than meets the eye as each incident is connected.

One chapter was bundled with each limited edition release of the Toaru Kagaku no Railgun anime DVD and BDs, with all of them together being equivalent to a single normal Toaru Majutsu no Index volume

Growth cheats? Infinite magic power? The ability to utilize all archetypes? What’s the point if instant death ends everything with a single attack?

High school senior Yogiri Takatou was on a school field trip when he woke up to a dragon assaulting his sightseeing bus, with the only ones still on the bus being him and his female classmate, the panicking Tomochika Dannoura. Apparently the rest of his classmates had been given special powers by Sion, a woman who introduced herself as Sage, and escaped from the dragon, leaving those that hadn’t received any special powers behind as dragon bait.

And so Yogiri was thrown into a parallel universe full of danger, with no idea of what just happened. Likewise, Sion had no way of knowing just what kind of being she had summoned to her world.

Zhou Xu, who had just graduated from college, suddenly received a call from his father.

“My son, since you have grown up, there are some things that a father should tell you.”

Zhou Xu: “Dad, how do you speak in a succinct manner? Half white or not, what TV series are you watching?”

“My son, it’s a showdown for my father. For my father, you are a giant of the devil. You are the son of the devil.”

Zhou Xu: “…Dad, I’m hanging up, I’m busy.”

“Wait, there’s one last thing. Aren’t you too young? Your mother arranged a blind date for you. See you.”

Zhou Xu: “Who is it?”

“Like you, the devil goddess at the opposite door.”

- Description from novelbuddy

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.