At the behest of the organization, Celeste becomes the bodyguard of Edward, the crown prince of Midland. While spending time together, she comes into contact with Edward's strength and vulnerability, and decides to protect him of her own volition. Edward also trains his mind and body so that he can protect Celeste.

"I love only you."

Two people who overcome many difficulties and are attracted to each other. However, the difference in social status between the Crown Prince and his personal guard stands in the way... A story of growth, battle, and love between two people who shoulder heavy roles and pasts.