I Became The Academy’s Blind Swordsman - Chapter 4

“You will hear many of his Death Eaters claiming that they are in his confidence, that they alone are close to him, even understand him. They are deluded. Lord Voldemort has never had a friend, nor do I believe that he has ever wanted one,” Dumbledore told Harry Potter with absolute certainty.But what if Voldemort did have a friend? Not just a friend but the friend? A millennia-old wizard, who learned the secret of Hogwarts from the great Four founders, and had his own goals to take over the world?To stop that ancient wizard, an ancient power is called upon . . . in the form of a girl. A Muggle-born at that.Christina Norton has powers beyond anyone's imagination but she is too caught up in the Chosen One Harry Potter's life and catastrophes. But as she starts to uncover the plans of Voldemort, she realizes someone else is working with him. Someone who wants her dead. Why? She doesn't know. She just knows she has to save her loved ones and Hogwarts from Malgino and for that she is ready to go to the end of the world.And fight whoever comes in her way.

The world is terrorized by the powerful Black Witch who has been sealed in the moon. Every ten years, the night of Hexennacht arrives and a chosen witch must battle the Black Witch in hopes of finally defeating her.

As the current decade’s Hexennacht approaches, a mysterious girl named Kagami Kagami arrives and meets Horinouchi Mitsuru, the daughter of the previous Hexennacht representative.

It takes place between Kyoukai Senjou no Horizon and the City Series, two other series by the author.

Hell Ghost Wang Wannian is born again, smiling and proud!
What?
Are you a soldier, will the tank drift?
You are a master, can you give birth to dragons and tigers?
You are a superman, can you call the wind thunder?
Excuse me, I am not targeting anyone, everyone in my eyes, it is rubbish!

- Description from Uukanshu (translated)

Meet Sora and Shiro, a brother and sister who are loser shut-ins by normal standards. But these siblings don’t play by the rules of the “crappy game” that is average society. In the world of gaming, this genius pair reigns supreme, their invincible avatar so famous that it’s the stuff of urban legend. So when a young boy calling himself God summons the siblings to a fantastic alternate world where war is forbidden and all conflicts–even those involving national borders–are decided by the outcome of games, Sora and Shiro have pretty much hit the jackpot. But they soon learn that in this world, humanity, cornered and outnumbered by other species, survives within the confines of one city. Will Sora and Shiro, two failures at life, turn out to be the saviors of mankind? Let the games begin…