Luna

The princess of the Empire. She is a young woman with long blonde hair, who wears opulent white garments and carries a silver rapier with her. She is described as being impeccably beautiful. She fears that if her brother inherits the throne that the three Great Families would unite and overthrow him in order to assert their strength and take over the Empire themselves. Her best friend is Kerr Charlotte. Initially, she has a very low opinion of Yu. But being trapped in the Demon Realm with him caused her to rely on him, open up to him and eventually develop feelings for him. She later becomes Empress and marries Yu, which legally gives him the authority to have multiple wives since only people of lofty statuses can do so. While in the Demon Realm, she becomes a half-demon after unleashing the Ancient Demon by being tempted under the influence of the Nightmares in the demon realm, trying to gain power to save the Flemish Empire from Ezes(as she doesn't know Yu's power before he defeats the demon and saves her). She knows that Yu is an Apostle and will keep his secret under the condition that he keeps her half-demon blood a secret and to bless and defend her Empire forever, which he accepts. She wields Legendary Thunder Spirit Sword Ashia one of the seven legendary swords which is inherited from her father which can also tranform to sword spirit and weild itself to protect owner/master but unlike Noah or Sylph who are willing to sacrifice themselves to protect master, Ashia dislikes Luna as she is weak to not bring out her true potential. Ashia has masochistic personality towards Yu and his thunder and only is willing to listen to him.