Yuusha

Yuusha is the Human realm's most skilled warrior, possessing unmatched mastery over swordsmanship and versatile magic. Though originally tasked with slaying the Demon Queen, he abandons his mission to seek a lasting peace by joining her cause to resolve the conflicts between their two worlds. He operates within the Demon Realm under the secret identities of the Black Knight and later the White Swordsman, hiding his true origin while developing a deep romance with the Queen.