Miko Kurono is a lesser-known streamer, "Necronomico," who plays video games for her small audience. She has been covering the hospital bills of her close friend and fellow streamer, Mayu Mayusaka, ever since she and other popular streamers mysteriously fell into a coma three months ago.

Desperate for money, Miko agrees to participate in a top-secret beta test for a cutting-edge VR game. After clearing the first level, she and six other streamers come face-to-face with the Old Ones—ancient, evil gods who have returned to take over the Earth but are currently trapped inside the VR world. Miko becomes enraged when she discovers that one of the gods, Cthulhu, has taken the likeness of Mayu and is the one responsible for her condition.

Alongside the others, Miko is now a part of the Old Ones' twisted game called the Cosmic Horror Show, where the elimination of all the players results in humanity's doom. However, knowing that the winner is granted a single wish, Miko sets out to beat the game and save Mayu.