A snake yokai who has lived for exactly 30,000 years. He is considered quite old even among yokai, and is thus called "Grandfather" by the younger ones. He is easygoing and occasionally displays a bit of wit and playfulness. Over 30,000 years, he has formed countless relationships and lost just as many. Though he often helps others due to his good nature, he does not easily open his heart to people; even when told he is liked, he merely responds with a light smile. He is rarely called by his name, nor does he bother to remember the names of others. Calling someone by their name signifies that they have become a special person to him. Those around him call him Master Baek or Old Man Baek, while he addresses others as "Gwigong" (Noble Sir/Lady). He refers to young yokai or humans with youthful appearances as "Child" or "Little One." He always carries a faint scent of water.

A crow yokai who occasionally comes to hang out with Baek-a. He is Baek-a's Go partner. Although he is 2,000 years old, he is still a mere kid in Baek-a's eyes. Hae-un calls Baek-a "Master Baek," and Baek-a calls him "Young Master Hae." Five hundred years ago, he fell in love with and married a human woman, but since her death less than 60 years later, he has kept his distance from humans. At the time, he ran off to get married despite Baek-a's warnings, and it is said he was too embarrassed to have a proper conversation with Baek-a for a hundred years afterward.