The students go about their daily lives while Riselia hones her skills as a vampire. However, they are all unaware they are experiencing the calm before the storm.

The city is under attack, forcing everyone on the defensive.

Leonis may be a demon lord, but he still has his honor. He will put an end to the invasion, but he must first draw a sword that will test his resolve before he can wield it.

Leonis’ platoon attends a commendation ceremony on the SS Hyperion, unaware of the sinister plot to kidnap the Fourth Imperial Princess.

The kidnappers accounted for many things, but they did not account for the interference of the legendary Demon Lord.