In 2028, Yosuke Aiba and Arisa Aiba welcomed their daughter, Seria. Growing up in a household of music lovers, Seria began to have contact with spirits as she grew older. Around the same time, the music app MiucS transformed from an AI that played music together to an AI that managed music.

Odysseus appears before Seria and the others. His demeanor is somehow otherworldly. Odysseus talks about creating a world without conflict through a "ghost concert" using MiucS. While at odds with Yukina, who aims to reclaim MiucS, Odysseus speaks to Rinku...

Back in the human world, the members of the TERA Ibaraki branch enjoy a brief rest at a hot spring resort. Meanwhile, Yukina meets with Tsutomu Saionji and learns that his wife, Reika, was murdered by Odysseus. Tsutomu tells him about the evolution of MiucS and Odysseus's true objective.

Yukina, Kaede, Akari, Rui, Sana, and Ichinomiya Manpei gather in front of Nero Castle. With Sana's guidance, the plan was to begin the recapture operation simultaneously with Seria's singing. However, Nero starts singing on his own, causing chaos inside the castle. Faced with this unexpected situation, each of their intentions begins to clash.

Riku joins a group of witches, while Nero prepares for his concert.

Seria is captured by Nero, and many of her friends remain trapped in the Phantom Realm.

Settei and the girls travel to the Phantom Realm to destroy MiucS' server.

Seria accompanies Riku to an abandoned theme park overrun with ghosts.

Seria and Rui are invited into the inner palace to seduce the ghost of Lord Iemitsu.

Seria joins TERA and visits a part of the Phantom Realm guarded by the ghost of a swordsman.

An organization of mediums known as TERA harbors Seria to protect her from MiucS.

While out with her friends, Seria hears singing. The voice belongs to the ghost of the great Cleopatra.