COTE : There is Something Wrong With Hikigaya - Chapter 35 - : Animals and Cages

Magic finally reached planet earth, but it was not like we expected. It came in the form of mystic energy!

After the age of awakening, all living things finally entered the path of evolution.

Mystic Beasts invaded earth, destroying the world as we knew it, but we survived as we finally gained the ability to utilize the energy that the beasts came with.

Mystic Warriors were born, and humanity finally found a moment of reprieve, but the Mystic Beasts were still winning.

Rex Vector, an apparently mystic energy-deficient sword genius who lost everything to the war turned out to be the last inheritor of an Ancient Bloodline.

On fully awakening his bloodline he was granted a system and his whole life changed for the better.

Life held much more in store for him though as the contents of his first system mission revealed a reality to him that he wasn’t sure he wanted to accept.

[You are hungry!]

[You must drink human blood within 24 hours!]

[Penalty for mission failure: Death!]

Perhaps it is the choice of fate. As a senior otaku, Qian Lingfeng got the “steel shell system”. However, when he swept the world with the system, became a local rich man, made all kinds of beautiful women, opened a harem, and realized the ultimate fantasy of thousands of otaku, he found that things seemed far from simple!
When the end comes, biochemical zombies suddenly come down, fierce beasts are in power, bloodthirsty zerg roam to kill the world, and human lives are comparable to dirt. Where will weak human beings go in this world? Is humanity going to be extinct? Or … can an otaku save the fate of the human race?

- Description from Novelupdates

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.