The year is 2045 in a world where singing is prohibited, and an app called MiucS creates and performs all music in place of humans.

While out with her friends, a young girl named Seria Aiba hears something she shouldn't: the sound of singing. What's more, the voice is coming from an otherworldly being — a "Great Ghost."

A group of psychic mediums known as TERA.

And the resonation of "Possession Requiem."

"This is the story of how I became a ghost."