Kim Yeonghui is a 19 year-old girl who had been kept inside the boundary in her family's mansion ever since she was a little girl. when her long-term personal bodyguard suddenly resign, Mingyu, a first-class bodyguard is hired to replace him. as yeonghui finally need to step out to the outside world, Mingyu need strategies to keep her safe from being attack by the enemies. He then begin to search for new members and form a team of 13 shining knights.