Operation Demon Castle Date!

Operation Demon Castle Date! summary:

Kukuru, a princess who wishes to meet her destined one, is taken away to Brosfell Castle and brought before the Demon Lord Diana, who confesses her desire to marry her. Believing that trying to escape on her own would be too dangerous, Kukuru proposes that before getting married, they should go on a date first. With Diana bringing out all the stops while Kukuru secretly looks for a way out, a date taking place in the demon castle begins.