What would the last human do in a world of demons

Demons appeared out of the gate on Oshima island; wielding mystical magic powers, and superior physical attributes, the immerging blue-skinned monsters easily took over japan and mobilized to destroy the rest of the world. in response, the United Human Army was formed, a coalition of all the world's military, governmental, and scientific powers in order to fight back the demons and their powerful magic.

Through many sacrifices and scientific breakthroughs, humanity managed to fight on equal grounds with the demons. they answered their powerful magic with augments, powers granted by the use of brain chips that allow humans to control gravity and elements, and anti-magic bullets and miniature nuclear warheads as a counter to the magically enhanced swords and armor wielded by their elite warriors. For 50 long, grueling years the war continued, leaving nothing but death, destruction, and hatred in its wake.

These are the memories of one human soldier who returned from the dead, only to find his world now inhabited completely by demons.