The game is set on the imaginary island-kingdom of Ruswal, where nights are plagued by Azure-blooded demons. Although it is dangerous for humans to leave their homes after dark, the brave knights known as the Curia are trained to fend off the ever growing threat.

Among them is Arnice, a warrior of great skill and the protagonist of Nights of Azure. While she’s skilled with a blade, her talents aren’t just a product of her training. Arnice has some demon blood herself and is actually the only human that has managed to touch azure blood and survive! This event hasn’t left her unscathed and its thrilling implications become apparent quite early on; among others, it allows her access to a set of impressive abilities including the power to summon monsters to her aid in battle.