Clevatess reigns as a powerful demon king over the dark lands. When the king of Haiden attacks his territory, Clevatess retaliates, destroying the kingdom by killing the monarch and all thirteen heroes sent to subjugate him.

Victorious, he discovers Luna, a baby from the Haiden royal family, and spares her, choosing to raise her himself. To aid in her care, he resurrects the slain hero Alicia using dark magic, binding her as an undead slave to prevent disobedience or escape. Luna's presence sparks his growing curiosity about humanity, prompting him to journey with her and Alicia to observe human societies firsthand.

Traveling under the alias "Clen," he adopts the form of a deceased young boy who once protected Luna. This disguise conceals his true demonic nature while diminishing his powers. He recruits Nelluru, a former slave, to act as Luna's nanny after she risks her life for the infant. Luna's influence moderates his inherent hostility toward humans.

Clevatess refrains from conquest unless provoked, focusing on protecting his domain and companions. His ongoing interactions with Luna and Alicia gradually reveal a more complex character beneath his initial role as a destroyer.