Yeoksal

To Ji-Han, the only son of the prestigious Choi family, Kim Seo-On has always been a thorn in his side. An adopted orphan, he acts as the eldest son, stealing his father's favor, and now trying to steal his future wife. Eventually, Ji-Han seeks out the shaman Yong-Han to ask him to kill Seo-On . The shaman offers a clever plan: to use a sex worker, as Seo-On is a man of excessive lust. One night, while the rest of the family is away, Seo-On, who has consumed an aphrodisiac, falls into a deep sleep. However, in a moment of carelessness, Seo-On opens his eyes...

In the frozen dawn of February, a game of hide-and-seek with a beast begins.

(Source: Ridibooks, translated)