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

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.