Kikansha no Mahou wa Tokubetsu desu

Summary

Another dimension that continues to taint our world, the Shadow World. Humanity is faced with the worst calamity, known as the Shadow Labyrinth. In spite of their desperate attacks, Desir Herrman and his friends lose their battle to the Destruction Dragon, Boromir Napolitan, and the world comes to an end. When Desir is convinced of his end, he opens his eyes... to find himself 13 years in the past. Desir has gone back in time to the enrollment ceremony of Hebrion Academy, the top school for mages in the Empire.

To change the future of impending doom, Desir reassembles his friends once again to save the world!

(Source: Crunchyroll)