What exactly is happiness? Ritsu Shikishima, a high school student who enjoys psychology, likes to ponder questions like this while spending his free time with his friends. His perfect world begins to unravel, however, when he hears a strange voice, obscured by static, pleading for assistance. This is the voice of, a beloved pop idol whose singing begins to have a negative impact on the world. The faces of Ritsu's friends and family become distorted by glitches as the sound of's voice transforms them into Digiheads: berserk monsters bent on annihilating all who begin to awaken to the true nature of their existence.