Some people would do anything to run away from life's problems. In The Caligula Effect: Overdose, the line between fact and fiction becomes blurred when people escape from the real world into a beautiful realm called Mobius. Created by a sentient vocaloid program named μ (Mu), Mobius transforms all of its inhabitants into high school students, and allows each individual to create their own "ideal self" within this realm. However, as you begin to remember fragments of memories from the real world, you realize something is wrong...