Deep in the underground, quirk and human experimentations were completed to make the ultimate heroes or villains, depending on who would pay the higher price. One night, they escaped out into the world.
Midoriya Izuku wanted nothing more to be a hero, but he is quirkless. No one believes he could make the mold and would always be worthless but them.
They always believe that they would be weapons and nothing more until Midoriya Izuku told them that they could the greatest heroes.