Hyun Bin has to live surviving as a man. Fate has come to trap her compassion in a mask like a bird blazing only in it's cage...---Hyun-bin grew up under the cruel hand of street gangsters, selling gum in the subway with her little brother. However, after an unfortunate event, Hyun-bin runs away and is taken in to be trained to become a bodyguard. However, she must hide that she is female, and pose as a man. And so, for eight years, she grows up as a cold, male bodyguard. But is this how she'll be forever?