Hyun-Bin found herself surviving on the streets, concealing her gender to avoid danger. Tragedy struck when her beloved little brother passed away, causing her to flee from begging and gangs- only to be taken in by a wealthy family. Despite her new circumstances, her life was far from ideal. She was subjected to rigid training daily while being tasked with protecting the innocent, princess-like Yae-Ha. The rules were strict: Hyun-Bin must defend Yae-Ha at all costs and keep her gender a closely guarded secret. Although this way of life was lonely and emotionally detached, it all changed when she met the delinquent Yun-Ha. A significant turning point that caused a collision between loyalty, duty, and the blossoming of love.