I Attack 10,000x Times Stronger - Chapter 12: Threesome Dual Cultivation Technique

The ordinary youth lacked the exceptional talents of his peers, yet he possessed a shocking heritage, bearing a mysterious bloodline and harboring the spirit of the Evil Dragon.A deadly incident caused the youth to fuse with the Evil Dragon's memories and his Martial Soul, his divine might shaking the heavens!The dormant dragon was startled awake, its roar shaking a thousand mountains.

After the Catastrophe, every rule in the world was rewritten.

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.

The world that nurtured the civilization which reached the pinnacle of magic was on the verge of destruction.
The last survivor transmigrated to the past, when the magic civilization started growing, as countless mages were still fumbling their ways through the thorny paths of magic knowledge.
He, who came from the end of the magic era, aim to reach the pinnacle of magic.

- Description from Novelupdates