It was said that Yuie flowers, which are native to Celestia, never bloom in the Netherworld. However, for some unknown reason, fields of wild Yuie flowers start blooming! The areas where the flowers are blooming suddenly have a refreshing feeling about them, kind of like Celestia. However, these flowers start spreading throughout the Netherworld at an alarming rate. Grosso and the rest of the Krichevskoy Group are convinced that this is part of an invasion by Celestia, and start pointing fingers at Laharl for striking up relations between the Netherworld and Celestia, and thus deem him unworthy of being the Overlord. What is happening in the Netherworld? What is causing this? Can Laharl stop the spread of the Yuie flowers!? This crisis can't be solved through pure strength alone... Laharl's worthiness of being Overlord is put to the test.