If your most recent brush with a Korean gwi is Gwi-Ma — the fiery, soul-devouring demon that looms over KPop Demon Hunters — then the spirits in The East Palace might have seemed familiar. Gwi-Ma and the new supernatural K-drama’s menagerie of gwi-mae and gwi-shin all share the root word gwi, meaning ghost or malevolent spirit in Korean. But instead of one Big Bad to defeat, The East Palace holds a diverse group of spirits who refuse to let go of the human world. Below, learn more about the realm of gwi, sorted by each type of spirit’s relative amount of resentment that keeps them anchored to the physical realm.

The gwi-shin: souls with a grudge

The backbone of Korean folk horror, gwi-shin are specters who never passed on because they have unfinished business in the mortal realm. One of the most world-famous examples of a gwi-shin is Samara Morgan, the white slip–clad woman with black hair obscuring her face who haunts The Ring and Ju-On (which inspired the Grudge series). In The East Palace, not all gwi-shin are equal, as they range from harmless to lethal, and the depths of their grievances are what differentiates them.

Common-gwi

At the gentlest end are the common-gwi. They linger out of longing rather than malice, and pose no real danger to the living. They tie themselves to a person, a duty, or a promise they can't abandon. 

Won-gwi

Then come the won-gwi, the ones who hold a grudge. As Gu-cheon explains, a won-gwi is a soul that cannot pass on because its resentment has calcified within them; the ghost even forgets who it once was, remembering only what it lost. In the show, their grudges take on physical form: as thick back lumps that gag them, or appearing charred and red-eyed, like the 13 court ladies who were burned alive in the palace’s salt storehouse. A won-gwi can only be freed once its source of resentment is addressed. 

Ak-gwi

At the far, terrible end of the spectrum is the ak-gwi. An ak-gwi is either an evil person who carried that evil into death, or a won-gwi that has done harm for so long it morphs into something truly decrepit. Unlike other gwi-shin, who want their specific grudges addressed, the ak-gwi are out for blood and will destroy anything in their way, including the innocent. When a rumor spreads that the same pond gwi-shin that killed the palace’s princes 30 years ago is back again and out for blood, some believe this type of evil is something only an ak-gwi could carry out. 

But the threat of the ak-gwi runs much deeper for Gu-cheon. As a ghost slayer, he can only cross into the Realm of Gwi by killing himself, and then claw his way back to the living world. Every trip burns away his own yang (meaning bright, living) energy, and if he loses too much of it, he risks losing his humanity. And if he ever sinks too far into the grief and resentment he holds from his past, he opens himself up to becoming an ak-gwi himself.

The gwi-mae: here for the vibes

A gwi-mae is not a ghost at all, as it was never a person to begin with: It’s a spirit formed from bad energy. Since the palace has been a den of greed and corruption, it’s the perfect place for all types of gwi-mae to fester. A gwi-mae has no soul, so it cannot be reasoned with or exorcised the way a gwi-shin can. There is no grudge to resolve, either. Born of energy, it feeds on yang from the people around it.

The series' standout gwi-mae is a Ggeomeoksali: a creepy, yet also somehow endearing creature with the round face, hollow white eyes, and chubby body of a baby. Where most gwi-mae are bound to a place, the Ggeomeoksali binds itself to a person, trailing after Gu-cheon in order to steal his yang energy — and his snacks — at every opportunity. Nam Joo-hyuk, who playes Gu-cheon in the series, tells Tudum that the Ggeomeoksali even rivals Saeng-gang (Roh Yoon-seo) as his character’s best friend in the series. “The Ggeomeoksali is a real bonus. A bonus [best friend],” Nam says.  

Elsewhere, the palace grounds hide all kinds of gwi-mae, from a bird-legged creature in the bamboo forest to a snake gwi-mae coiled around the queen dowager. 

How to fight the gwi

As all-powerful as the gwi can seem, Gu-cheon has a set of sacred weapons to fight them. Peach wood branches that grow facing toward the East are particularly harmful to gwi-shin. He fights with peach-branch swords that corrode and drop away the moment they plunge into a gwi-shin, which is why he carries 20 at a time. Stronger still is wood from a jujube tree struck by lightning, which Saeng-gang gathers for him to carry into the Realm of Gwi to fight ak-gwi. Working from the human side, shamans string up geum-jul, sacred straw roped with gwi-repellent items, as well as bu-jeok, pieces of paper containing spells; they use them in ceremonies to drive away the gwi. 

But those tools only go so far, as they work on common-gwi and gwi-mae but not the stronger won-gwi and ak-gwi. Once a gwi’s resentment has hardened into a won-gwi or an ak-gwi, the only way to get rid of it is to help settle the grudges that tie it to the human realm. But as Gu-cheon and Saeng-gang come to learn, some expressions of rancor are easier to address than others — other times, the ak-gwi may be too far gone.

In their mission to find the pond ghost that’s haunting the East Palace, Gu-cheon and Saeng-gang find no shortage of gwi-shin and gwi-mae, as the palace is a wellspring of resentment, bitterness … and just all-around rancid vibes. It’s a place where even the most powerful are one misstep from being swallowed by their own darkest secrets. For every ghost these two lay to rest in the Realm of Gwi, someone still breathing in the human realm tightens the same knot of ambition and fear that made those ghosts: a grandmother guarding the secrets of the royal bloodline, a king protecting the throne’s legitimacy, and a royal court that aims to win rather than govern. The gwi may seem like the most fearsome threats, but it’s the living who keep the palace haunted.

The East Palace is now streaming.