Ten years ago earth was invaded by other dimensional beings through portals causing chaos across the planet morden weapons like guns and missiles didn't work against them because of a mysterious energy called mana surrounding them, even after all the nations join together to fight against these monsters they failed

But when humanity was in despair the mana leaked from the dimensional portal affected some humans causing them to mutate which resulted in giving them super powers. These mutated humans were capable of fighting against the monsters

These mutated humans came tobe known as heroes, finally mankind got a new hope in their war against the monsters. A new world order was created every country tried their best to rope in these heroes by proving them special status and wealth

Year 2035

As always humanity easily adapted to the changing world new guilds consisting of heroes were formed, Nowadays thanks to the heroes people are not afraid of the monsters and the world continued to function as before with some changes of course, becoming a hero has become the most favoured career while S class heroes are considered top celebraties with lot of wealth and fame and some guilds hold more power than government themselves, the portals from which monsters came out became dungeons which humanity now only sees it as a place to farm resources like mana crystals and monster corps