[XRB Research Bureau has intervened, please cooperate.
In H2092, after the world experienced the fourth mass extinction of organisms, humans continued to evolve in order to survive. Among them, a very small number of the best differentiated into more powerful human races, sentinels and guides.
At the same time, under the influence of a substance called Y factor, a type of extremely terrifying creatures was born in this world. Most of them have extremely strong attack and destructive power, and have various shapes, so they are collectively called alien creatures.
These alien creatures are also divided into six danger levels: S, A, B, C, D, and E.
Therefore, in order to protect mankind, a professional department established specifically to deal with these alien creatures and related cases: the XRB Research Bureau, was born.
There are many top sentries and guides gathered here, and they use their abilities to protect everyone.
Concept: The world is not black and white.
