Inheritance of the four horsemen of the apocalypse :

In 2010 alot changed in the world, portals opened everywhere. at first no one knew what they were. then three days later the portals color changed from blue to red. two days after, the unimaginable happened. monsters come forth from the portals varying from skeletons, orcs, goblins, demons, trolls, animals that were anything but normal. and in some cases, dragons. humanity despaired for their modern weaponry had little to no effect on them, many were killed within days. at least 20% of the world's population was wiped out within four days. on the seventh day, it was over 40% of the human population. but then natural disasters started left and right, the world expanded by a third, some islands and peices of land started floating, strange plants started growing, animals started mutating, and then in humanity's despair, A ray of hope revealed itself and some humans started, what they called Awakening, they gained magical abilities, abnormal strength and speed from then on humans, who were originally running and hiding began fighting back, they learned that to effectively kill monsters they needed special weapons that could either be found in the portals, which they started calling gates, or forged from monster corpses. they gave monsters and themselves rankings, from F to SSS. all because they awakened as an S rank doesn't mean they would have S rank strength they would have to reach that rank through training, meditating and absorbing the newfound energy in the very air, which they called mana, there was also special ingredients which they could consume and it would increase their progress. After five years of brutal fighting, humanity had regained over 50% of the planet. the other 50% remained overrun, that point they started to raid the gates, they figured out long ago that five days after the appearance of a gate monsters would come out, after entering and clearing a gate they would have to kill the gate master. the gate Master was much stronger then the normal monsters in the gate, they would often require a team of awakened of the same rank to take it down. five hours after the gate Master was killed the gate would close, similar to monsters and humans gates were given ranks as well. many children also awakened thus they started building schools for awakened and soon things turned fairly normal, the world was once again at peace. except for one seemingly normal kid, it's with him that this story starts and many secrets revealed.