An individual participating in Darwin's game possesses a stealth-like ability known as "Steath," which renders them invisible, but only if their entire body is concealed.
Spoilers:
He is revealed to be Kyoudas teacher, Katou-sensei.
A person named Sudou Kaname who was not aware of it gets asked to test out an unknown mobile game application called Darwin's Game. However, after discovering that there is no option to exit the game,...