One who traverses 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, allowing him to fight ghosts directly on their own turf. He was summoned to the palace by the King. The reason he can traverse the spirit world is linked to the guilt he carries from a past 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, outspoken, and as learned as any scholar, she is a court lady with a mysterious ability to communicate with ghosts—a power matched only by the weight of her secrets. She is the King's daughter and the Crown Prince's half-sister. Her ability to communicate with ghosts is a hereditary trait of the royal family. She was exiled from the palace as a child when her mother was framed and ousted, living as a princess in exile. After her mother was later poisoned under mysterious circumstances, she enters the palace under the King's orders to assist Gucheon in eliminating a pond ghost, seeking to uncover the truth behind her mother's death and claim her revenge.

One who hunts the ghosts in the abyss. Male. The figure who secretly summons Gucheon and Saenggang to break the curse haunting the palace. He was the illegitimate son of the late King and a concubine of lowly court lady origin, Lady Suk-bin Choi. He ascended to the throne after all his legitimate half-brothers died. However, due to his birth status, he has a strained relationship with the Queen Dowager, who has looked down on him since his days as Crown Prince. Now, 30 years into his reign, his first and second sons, Princes Jangpyeong and Yunpyeong, followed by his third son, the current Crown Prince, have all been found dead in the pond—apparent suicides. Despite the Queen Dowager's claims that this is the curse of a pond ghost, he refuses to believe in spirits, asserting that no ghost could touch the royal bloodline. However, when his youngest son, Grand Prince Yeongan, who hasn't even been invested as Crown Prince yet, begins to be tormented by spirits, he finally orders Saenggang and Gucheon to purge the palace of ghosts.

A ghost-imp that lives by sucking the yang energy of the living. Doesn't cause serious harm (other than taking your energy). Cute...