On one occasion, Mai encounters a chilling game called Nightmare. Despite hearing negative rumors about it, she has no desire to play. However, her situation changes when an enigmatic voice presents her with a dilemma: either participate in the game or risk losing those dear to her. Although playing poses a threat to herself, Mai decides to do so in order to safeguard her loved ones. It's important to note that dying within the game carries real-world repercussions. To make matters worse, her classmates Asagi and Sugiura have also become ensnared in the sinister game. They are left with no alternative but to collaborate and overcome it together.
Online! has been licensed in English by Yen Press under the JY imprint.