Online! The Unbeatable Game

One day, high schooler Mai finds a mysterious game called Nightmare—a popular game that you have to keep playing every day, or your body will slowly start to shut down. And she's not exactly a pro gamer. Still, in the hopes of beating the game completely, she joins forces with shy Asagiri and handsome-but-difficult Sugiura to form the Nightmare Strategy Club! (from Yen Press)