One day, Mai comes across a creepy game called Nightmare. She's heard bad rumors about it, and she's got no interest in playing. That is, until a mysterious voice gives her a choice: play the game or lose everyone she cares about. She'll play to protect her loved ones, but that means putting herself at risk. After all, dying in game has terrible, real-word consequences. To make matters worse, her classmates Asagi and Sugiura have been caught up in the twisted game too. They have no choice but to work together to beat the game!