Just when he thinks it's the end, Desir wakes up 13 years in the past. Can he make the changes needed to save the world from destruction?

The world is on the brink of destruction after a devastating ten-year war in the "shadow labyrinth." Desir Arman is one of the last skilled magicians left standing, but even he is no match for the formidable foe threatening humanity's very existence. Just when he's certain the end has come, he is sent back in time to his early days of studying magic at the prestigious Hebrion Academy. With this rare second chance, Desir is determined to save not only himself but also the friends and comrades he once lost. Armed with the knowledge of what their future holds, can his efforts make a difference, or are they all doomed to relive the same terrible destiny? Based on the hit novel.—MyAnimeList

Shadow Realms have ravaged the earth and decimated almost everyone in their way. The survival of humanity hinges upon the success of just six mages, including analytic fighter Desir Herrman. The remaining heroes make one final stand to end the bloodshed...but to no avail. Desir closes his eyes on what should be the end of his life-only to open them and see the beginning of his school days?. Desir has returned thirteen years back to the past, where he's been given another chance. A chance to see the loved ones he lost, a chance to meet his fellow warriors again, and a chance to save the world..—Yen Press

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.—Crunchyroll

"I won't let my loved ones die again now that I'm back!" The Shadow Labyrinth is the most terrible situation humanity has ever encountered. One of the six human survivors still alive is Desir Arman. The six made an effort to escape the last stage of the labyrinth, but finally were unsuccessful, and the world ended. But just when Desir believed he was going to die, the world is revealed to him. it was thirteen years ago? Desir is transported back in time to the period when he joined in Havrion, the best magic school in the country. In order to rescue the planet and his loved ones, he is ready to alter the history after being reunited with his cherished pals. There are still three years till the Shadow World appears. Change the past and assemble strong allies to save humanity.—Bilibili TV