Heaven's Fall

Earth, being the only planet that can sustain life for more than 2000 years of human civilization, was in a state of war due to the discovery of a grimoire that contains the details about the power of the soul, mana.
The bloody war was considered the "The Last World War" or "War of the Nations."
When all of the remaining nations gathered into 2 different groups as per 3 continents in each group; the 2 continental nations shared all of their technologies and knowledge, completing the Final Covenant' event recorded in history.
In the year 2090, they then began to launch themselves into space, marking the beginning of space colonization; only to leave a few millions of people to take care of Earth.
After a few decades of somewhat peacefulness, a distress signal was received. The first galactic war starts, but due to an unfortunate event a ship's space jump drive was in critical condition.
When the last deciding operation ''Sky's Drop'' went without a hitch to success in the last minutes of the war, the damaged reactor produced a series of never before seen energy fluctuations. As the ship was exploding from the energy anomaly a space-time distortion wormhole appeared and..... it disappeared.

In another world, a young man woke up from a fleeting dream of a vicious and merciless war.