A mysterious pandemic called "Kleine-Levin Syndrome" has infected nearly half of the human population, causing terror around the world. As the pandemic worsened, a famous gaming company created a game called "FOS" (Fantasy Online System), which successfully lowered the level of fear and depression among everyone around the world. One day, a high school student named Ethan received a mysterious message while playing FOS from someone named Athena.  The message referred to the location of the cure formula to end the pandemic, which was inside of the game. But, it turned out there was a wicked side that was after the formula. Would Ethan manage to find it and end this pandemic?