The spotlight finally shifts to the most elusive member of the Misfit Class: Purson Soi. Known for his literal ability to fade into the background, Purson is forced into the open as the school prepares for the spectacular Music Festival. To stay in the Royal One, the class must perform a musical ensemble that stuns the entire academy, but they face a major hurdle—they need a lead musician who can play with soul.

Iruma, ever the selfless mediator, discovers Purson's hidden talent for the trumpet and begins a "selfish" mission to convince him to share his gift with the world. However, the stakes are raised when the legendary demon musician Amduscias Poro arrives at Babyls, bringing with him a connection to the vanished Demon King Derkila. As the Misfit Class practices their jazzy performance, the festival becomes a stage not just for music, but for hidden identities and the awakening of a new generation of demon leaders.