Male, Gucheon.

He lived in a temple before being abducted by the King. The reason he lived at the temple is that the nearby river is where his mother passed away.

His mother had spiritual powers and was a shaman. But when she conceived a child (Gucheon), the god she served was enraged and sent a curse. Eventually, the mother, suffering from the curse, fell into the river with Gucheon.

But the only one who survived was Gucheon himself.

He survived even after being underwater for over fifteen minutes and was taken in by the temple. Since then, he has seen all sorts of ghosts and spirit-imps, learning how to deal with them.

After being abducted by the King, he was given a life-threatening threat/order to forcibly eliminate the ghosts of the Eastern Palace. Formally, he is a geomancer sent by royal decree. He doesn't know a thing about geomancy, though.

Female, Saenggang.

The younger sister of the Crown Prince Ghost and the daughter of the King. However, she was exiled from the palace with her mother.

The reason for the exile? Well, it's because she knew the 'secrets of the palace'.

Like her brother, the Crown Prince Ghost (when he was alive), she can sense ghosts—through sound. That is why His Majesty attached her to Gucheon's side for surveillance. ...Though it seems that wasn't the original intended use.

Male, the King.

Everyone else addresses him as 'Your Majesty' with respect. He abducted Gucheon to protect his son, 'Prince Yeongan', from the Pond Ghost. In truth, he only cares about Yeongan's life and doesn't care about Gucheon's life at all. Therefore, he does not let Gucheon leave the palace for fear he might escape.

The Crown Prince Ghost, Saenggang, and Prince Yeongan are all his biological children.

A spirit-imp, Kkeomeoksalai.

It is a spirit-imp that lives bound to a person rather than a place. Spirit-imps are usually created by the sinister energy of nature or the negative power of humans.

It doesn't really make any sound, so Saenggang doesn't sense it, But for Gucheon, who identifies ghosts by sight...

...Well, yes, that's how it is. Got it? (?)

Male ghost, the Crown Prince.

He is the ghost with the greatest grudge in the palace. Because of this, he is the strongest ghost in the palace, and his grudge stems from the fact that he could not become King. He was poisoned by the toxin his father (the King) fed him before he could ascend. Before dying, he said he would become the 'true Pond Ghost'.

Female ghost, a concubine.

In the past, when a concubine first conceived the child of the late King, the Queen Dowager (who was the Queen at the time) framed her and caused a miscarriage.

"I shall dry up the lineage of the Eastern Palace!" Shouting this, she was the last concubine to jump into the pond. She became a ghost and rooted her grudge in the waters.

Female ghosts, palace maids (total of 13, apparently).

「The snake's skin killed the dragon's cub」 Using this writing as a pretext, the palace maids were locked in the salt storehouse and burned to death.

The one who set fire to the salt storehouse was the Queen Dowager, who was born in the Year of the Snake. (In the Donggung series, a battle with Gucheon takes place in front of the Queen Dowager's Buddha statue...... I forget which episode it was) The dragon's cub referred to the Crown Prince, and she burned the maids to death out of fear that she would be identified as the culprit.

She coarsely ground the bones from the corpses of the dead maids, put them in a jar, and sealed them in the salt storehouse with talismans and ropes (a precaution to prevent their grudge from threatening the royal family).

The seal, which should not have been broken, has been broken by someone.