MTL - Close Combat Mage - Chapter 358 Air fortress

Waking up again in his seventh reincarnation, prince Jing Beiyuan found himself back in time, when everything had yet to be set in motion. Having been given a second chance, Beiyuan had to survive court and decide whether it was finally time for him to let go of his feelings; all while trying to handle the youthful, innocent force of nature who had suddenly barged into his already complicated life.

- Description from Novelupdates

Reyhan Alther died at the age of 20 and was reincarnated… as the wind. Formless and directionless, he drifted through a new world filled with wonder and cruelty. But from that breeze, everything began. With a mysterious power called the Divine Spirit System, Reyhan slowly rose—guiding spirits, gathering followers, and changing the course of the world. From a lonely gust, he became a figure known as Father… even to the gods.A battle of fate awaits. But before that, there's still time for the wind to whisper… and maybe crack a small joke or two.

The world was once at war with 10 alternate worlds. This was known as the Concept War and our world won 60 years ago. All of this was concealed so no normal people are aware of this fact in the current time.

After the death of his grandfather, the high-school student Sayama Mikoto is suddenly summoned by the giant corporation IAI. He learns this world is headed for destruction due to the acceleration of the Minus Concepts. To prevent this, negotiations must be undertaken with the survivors of the other parallel worlds so their 10 concepts can be released.

And so Sayama is caught up in the final battle to clean up after the Concept War which left behind so much enmity.