Emi was once a childhood prodigy at karate however, an injury forced her to quit. She now works at a hospital as a security guard barely making ends meet. Her life changes when she saves a stranger from a sudden attack. The stranger turns out to be the sole heir of the hospital and hires her on the spot. Her job is to protect him and also to find the people trying kill him however, as she continues protecting him, she realizes that there is something much darker surrounding her new boss.