In a realm where angels and devils exist in a fragile balance, a boy born with demonic origins has a singular purpose: to protect Aria, a powerful 21-year-old angel. Though the boy is a devil by nature, he was created for the specific task of guarding Aria from the many dangers that threaten her life and the world they inhabit. His existence is marked by a binding oath, and despite his dark heritage, he has been raised with an unwavering devotion to the angel he must protect.
Aria, a young angel with immense abilities, has always lived a life of duty and responsibility. Despite her strength, she is unaware of the full extent of the dangers surrounding her. Her powers are coveted by dark forces, and her very existence is central to an ongoing battle between light and darkness. As she navigates her own inner conflicts, Aria begins to realize that the world is not as simple as she once believed.
The villain, a powerful and malevolent force, seeks to harness Aria's powers for their own dark agenda, threatening not only her life but the delicate equilibrium between the celestial beings. As the story unfolds, the boy and Aria must form an unlikely partnership, with their fates intertwined in a battle against the villain's growing.