Kaname Sudou, a high school student, is invited by a classmate to play Darwin's Game, a mobile game he has never heard of. However, as soon as he starts the program, a green snake appears from his phone screen and bites his neck, knocking him unconscious. After waking up in the infirmary with no visible evidence of a snake bite, he is instructed by the school to take the rest of the day off. Despite being perplexed by what has occurred, he dismisses the odd event as a hallucination and takes the train home. Unfortunately, his curiosity gets the best of him and he utilizes the program once again. Kaname exhales as the program looks to be similar to any other fighting game.