One who crosses into the spirit world. Male. An arrogant ghost-slayer. After experiencing a tragedy in his childhood, he gained the special ability to cross into the spirit world and fight ghosts directly. He was summoned to the palace by the King. The reason he can cross into the spirit realm is linked to the guilt he carries from a childhood incident where he and his shaman mother fell into a river; he was the only survivor, while his mother drowned.

One who hears the sounds of the spirit world. Female. Haughty and outspoken, she is a court lady whose knowledge rivals that of a scholar. She possesses the strange ability to communicate with ghosts and holds a secret as extraordinary as her power. She is the King's daughter and the Crown Prince's half-sister. Her ability to communicate with ghosts is a trait that appears in the royal bloodline. She was exiled from the palace as a princess when her mother was framed and ousted. Later, while her mother was poisoned under mysterious circumstances, the King summoned her to the palace to help Gucheon eliminate a pond ghost. She enters the palace to uncover the truth behind her mother's death and seek revenge.

One who hunts ghosts in the abyss. Male. The one who secretly summons Gucheon and Saenggang to break the curse haunting the palace. He was the illegitimate son of the late King and Lady Suk-bin Choi, a concubine of lowly origin. He ascended to the throne after all his legitimate half-brothers died. However, he has a strained relationship with the Queen Dowager, who has looked down on him since his days as Crown Prince for being the son of a court lady. Now, thirty years into his reign, his first and second sons, Prince Jangpyeong and Prince Yunpyeong, followed by his third son, the current Crown Prince, have all been found dead in the pond, apparently by suicide. Despite the Queen Dowager's claims that this is the curse of a pond ghost, he refuses to believe in ghosts, insisting they cannot touch the royal bloodline. However, when his youngest son, Prince Yeongan, who hasn't even been named Crown Prince yet, begins to be tormented by spirits, he orders Saenggang and Gucheon to purge the palace of ghosts.

A spirit-imp that lives by sucking the yang energy of the living. Doesn't really cause much harm (except for eating yang energy). Likes rice cakes. Cute...