Male. Can see Gwi (ghosts). A ghost-slayer. After experiencing a tragedy in his childhood, he gained the special ability to cross over into the world of Gwi, allowing him to fight ghosts directly in their realm. He was forcibly summoned to the palace by the King. Since then, he has been working with Saenggang to exorcise the pond ghost that threatens the King and Crown Prince Yeongan-gun. (Source: Namuwiki)

Female. Can hear the voices of Gwi (ghosts). A haughty, bold girl who is as knowledgeable as any scholar. She was expelled from the palace due to her strange ability to communicate with ghosts, but was brought back by the King to assist Gucheon in his exorcism work. She knows that Gucheon is not a geomancer, but someone who came to exorcise the palace ghosts. The King's daughter. (Source: Namuwiki)

Male. He seeks to find and destroy the pond ghost that continuously tries to end the royal bloodline. Previously, when the pond ghost possessed his son, Crown Prince Yeongan-gun, putting him in mortal danger, he threatened Gucheon and ordered him to wipe out the ghost. He brought Gucheon into the palace under the guise of being a geomancer. He also brought Saenggang, his daughter whom he had previously expelled, back into the palace disguised as a court lady. He cannot see ghosts or hear their voices. (Source: Namuwiki)

Cannot speak. Gender: None (Ghost). Lives by consuming human yang energy (likely human life force). A Gwimae (ghostly sprite). Not a ghost lingering in the living world due to grudges or unfulfilled desires. Occasionally found or seen around Gucheon. Seems to follow Gucheon everywhere.

The King's stepmother (the legal wife of the late King). She has looked down on the King since his time as a prince because he was born to a lowly court lady, and their relationship remains poor. As the princes suffer one misfortune after another, she tries everything to drive out the pond ghost. (Source: Namuwiki)

The King's son. He is currently bedridden due to the pond ghost's curse. Initially, he suffered from convulsions and let out horrific screams. While the screaming and seizing have decreased, his physical condition has visibly deteriorated. He cannot speak and has difficulty moving. He remains bedridden, battling his illness every day.

He wants to place his son, Inha-gun, on the throne. Seeing the King order others to eliminate the pond ghost, he brought a male shaman (Baksu) into the palace. He is close with the Queen Dowager.

Entered the palace following Iksang-gun. He knows of Gucheon and Saenggang but doesn't really know them as they've rarely met. He intends to eliminate the pond ghost according to Iksang-gun's wishes, but in the process, he ends up interfering with Gucheon and Saenggang's exorcism efforts.

A ghost. Appears as a maiden ghost. A ghost who was poisoned to death due to the Queen Dowager's jealousy. She seeks to sever the King's entire bloodline.

Appears black or red; it resembles the living world but is not the living world. It is the space where ghosts reside. No humans exist in this space except for those who have entered the world of Gwi. A space where ghosts are visible and present. One can reach it by tying a rope to a tree next to the palace pond, looping the rope to choke oneself, and entering the pond. It is extremely dangerous. One loses a significant amount of yang energy in this space.