Yōkai (妖怪) are apparently a are a class of supernatural monsters, spirits and demons in Japanese folklore.
Naver Dictionary translates this term as '요괴', but I am wondering if the word 요괴 refers to spirits and demons in a general sense (and perhaps if there might be some Korean '요괴'?), or if it's simply a transliteration of the Japanese term and understood to refer only to a Japanese concept of supernatural beings.
As a Korean native speaker, I think when Korean people refer to yōkai(妖怪)s we say:
도깨비, when we refer to some imaginary monsters, close to spirits, having the form of humans or other animals. They are usually spooky and carry some bat with needles, often said 도깨비 방망이. There are some songs for children such as 산도깨비.유령(幽靈), when we refer to ghosts.귀신(鬼神), when we refer to some spooky spirits with sorrow. e.g. 달걀귀신, 처녀귀신.괴물(怪物), when we refer to physical monsters which have extraordinary forms.The word 요괴 is not used that often; it got popular recently because of the Japanese animation 요괴워치(妖怪ウォッチ; Yōkai Watch).
요괴 = 요물 = monster
Korean call it 도깨비 frequently. But 도깨비 is typical example of 요괴.
요괴 is a thing having natural power. If the power is good, then we call it a god.
Typical example of good 요괴 is Sonokong (or Monkey King) who is a main character in China movie.
Corresponding example in western is wolf man, or vampire.
In China movie or old Korean drama series, 요괴 is frequently appeared.
구미호 = fox with nine tails : It was appeared in Korean movie long before. Roughly let me introduce. There is a fox of age 1000. So if she have 100 dates with man, then she will become a real woman. But she did not fill 100 so that she died.
@귀신 = ghost = thing after death of man : For instance, main character in the romance film "Ghost" in 1990.
귀신 is not 요물.
