- Drama: Gu Family Book / Kang Chi, the Beginning
- Revised romanization: Gugaui Seo
- Hangul: 구가의 서
- Director: Shin Woo-Cheol
- Writer: Kang Eun-Kyung
- Network: MBC
- Episodes: 24
- Release Date: April 8 – June 25, 2013
- Runtime: Mondays & Tuesdays 22:00
- Language: Korean
- Country: South Korea
Choi Kang-Chi ( Lee Seung-Gi) is legendary gumiho that is half human and half animal. He struggles to live his life as a human and also falls in love.
Seo-Hwa (Lee Yeon-Hee) is the daughter of a noble family, but her father is branded a traitor by Jo Gwan-Woong (Lee Sung-Jae) and beheaded in front of her. Afterwards, Seo-Hwa and her younger brother Jung-Yoon (Lee Da-Wit) are handed over to a gisaeng house. Seo-Hwa refuses to become a gisaeng or enter the house. She is then tied to a tree for 3 days before passing out from exhaustion.
Meanwhile, Koo Wol-Ryung (Choi Jin-Hyeok) is a spirit protector of Jiri Mountain and possesses eternal life. Koo Wol-Ryung is also full of curiosity and wanders around the human world. One day, he sees Seo-Hwa tied to a tree by the gisaeng home and becomes interested in her.
Seo-Hwa is unable to watch her younger brother being beaten because of her. She finally succumbs and agrees to become a gisaeng. She then learns she will have to spend the night with the man that killed her father. With the help of her servant, Seo-Hwa escapes into the mountain with her younger brother, but they become separated. Seo-Hwa is saved by Koo Wol-Ryung, but her younger brother is caught by a slave hunter.
Seo-Hwa wakes up in front of Koo Wol-Ryung. They enjoy their days together and fall in love. Koo Wol-Ryung decides to become human to be with her. In order for Koo Wol-Ryung to become human, he must refrain from helping people, eating meat and hiding his real appearance for 100 days.
11 days left before Koo Wol-Ryung becomes human, Seo-Hwa is caught by soldiers and flees from them. Tragedy occurs, but Seo-Hwa eventually gives birth to a baby fathered by Koo Wol-Ryung. The baby is later discovered floating in a basket along a river. One of the noble men names the baby Choi Kang-Chil.