Choi Kang-chi (Actor Lee Seung-Gi)

His father is Koo Weol-ryeong, a guardian spirit (守護神獸) of Mt. Jiri and his mother is Seo-hwa, making him a half-human and half-animal. Unbeknownst that he was born half-human and half-animal, he is abandoned by his mother who left him floating in a basket in a river. He is found by merchant Park Mu-sol who runs one of the largest inns for merchants. Kangchi is impulsive, reactionary, and uses physical force before thinking twice. He starts life anew after encountering Dam Yeo-wul and Yi Sun-shin.

Dam Yeo-wul (Actress Suzy, member of MISS A)

She joins her father who was tasked with the job of investigating a series of murders by Yi Sun-shin. She crosses paths with Kangchi who is falsely accused of murder. While Kangchi always causes trouble, Yeo-wul discovers his innermost secret, which makes her feel sympathy for him. Even after knowing the truth that Kangchi is half-human and half-animal, she trusts that he will not harm people and stand by his side. She is the only person who can calm down Kangchi when he goes on a rampage.