A superhuman is a person able to create feats impossible to ordinary humans.
Even though they became popular after the invasion of Earth, they already existed long before that. Every time a calamity happened to be it, disease, drought, pest, earthquake, etc... These events will give birth to the appearance of new superhumans.
Kinds of superhumans.
There are two kinds of superhuman,
Awakeners, are lucky people that are awakened when a calamity happen. Some of them are ordinary before their awakening and sometimes there is no correlation between their previous life and the abilities that they obtain. They wear a runic mark that automatically appears on their arms, the Valknot.
Martial artists, their appearance are less random, thanks to the shackle removed in their genes they can train till their body and mind reach a terrifying level.
When martial artists reach a certain level, a runic mark will appear on their arm, Aegis.
Mixed superhuman.
There are cases of awakeners with martial art talents since the awareness can still the knowledge of the people that they kill.
There are also cases of martial artists awakening to the supernatural. In this case, they will wear the two different runes on both of their arms. These martial artists belong to the two systems.
The counterattack system.
It is a system treated to help the awareness in their contest to the other worlds. It functions exactly like in a game.