After finding out about the involvement of Angels in the Earth Defense Force's plan to invade the Netherworld, Flonne decides to return to Celestia to confront Seraph Lamington about this. To her surprise, Laharl, Etna, Captain Gordon, Jennifer and Thursday agree to come along as well.
When they enter Celestia, the group are surprised to find none other than Mid-Boss waiting for them. Instead of his usual hijinks, Mid-Boss acts seriously and challenges them to one more battle, and disappears upon his defeat.
Laharl and his friends continue their journey through Celestia, defeating the Angels that confront them. Before long, however, they are greeted by a number of high level demons hired by Vulcanus. Just as their fate seems bleak, Kurtis appears in the form of a Prinny, and helps them defeat the demons.
Along with Kurtis, the group enters the Seraphic Sanctuary, where Seraph Lamingtom resides. Using the combined power of their attacks, they succeed in breaking through the invincible barrier and enter the Sanctuary. Before they can meet Lamington, however, they run into Vulcanus who wishes to defeat them once and for all. The team manages to prevail and Vulcanus flees before them, hoping to decieve Seraph Lamington. Luckily, the Seraph sees through his deceptions and transforms Vulcanus into a helpless flower. He then does the same to Flonne as a punishment, when she confesses her deeds to him. Stricken by grief and anger, Laharl attacks Lamington, defeating him.