3 years ago, Choi Moo Gak lost his younger sister who is one of the victims of "X" murder case. "X" murder case was assumed to be werewolf's fault where they put X-formed slit in the wrist of the victims they killed. Choi Moo Gak had been traumatized by his sister's death. After 2 months of no sleep and constant pain, he fainted and was admitted in the hospital for 2 weeks. When he woke up, he lost her sense of taste, unable to feel pain and can't feel if he's full or not from eating. He became emotionless, and speaks in monotone. He left his job in the aquarium to become a police officer and at the same time werewolf hunter. Oh Cho Rim hates herself for having a werewolf blood. She is totally human in terms of appearance and don't transform during full moon nights except with her eyes. It turns emerald during full moon. She also inherited the werewolf smelling sense and she runs fast but not as fast as a pure werewolf. Choi Mo Gak, while catching a suspect, bumped Oh Cho Rim that caused slight wound in his head and unfortunately lost the suspect but thanks to Oh Cho Rim's special hidden powers, they caught the suspect later on. Knew each other. Caught suspect together. Fell in love. Unknowing the naked truth behind their lives...