妖怪
ようかい
youkai
= a supernatural creature, spirit, or monster from Japanese folklore
妖怪 is the vast and strange family of Japanese folklore creatures, the umbrella term that covers shape-shifting foxes, river-dwelling kappa, faceless ghosts, and a thousand other beings that haunt the edges of the ordinary world.
妖怪 refers broadly to supernatural beings in Japanese folklore, from mischievous tricksters to genuinely frightening monsters. It is a category rather than a single creature, so a kappa, a tengu, and a tanuki that fools travelers are all 妖怪. The word often overlaps with お化け (obake) and もののけ (mononoke), but 妖怪 tends to sound the most neutral and encyclopedic, the term a folklorist or a museum label would use.
Use 妖怪 when you mean the general category of folklore creatures, and reserve specific names like 河童 or 天狗 for individual types. Note that 妖怪 is not the same as a ghost of a dead person; that is usually 幽霊 (yuurei). Mixing the two is a common slip, since both are supernatural but belong to different traditions.
妖 means bewitching, weird, or uncanny, and 怪 means mysterious or suspicious, so together 妖怪 stacks two ideas of the eerie into one word. Both characters are read with their on’yomi here, よう and かい, which gives the compound a slightly formal, classifying tone compared with the more folksy お化け.
Everyday use
この町には、橋の下に妖怪が住んでいるという言い伝えがある。
Kono machi ni wa, hashi no shita ni youkai ga sunde iru to iu iitsutae ga aru.
This town has a legend that a youkai lives under the bridge.
Casual / Social Media
妖怪の図鑑を集めるのが子どもの頃からの趣味なんだ。
Youkai no zukan wo atsumeru no ga kodomo no koro kara no shumi nanda.
Collecting illustrated guides to youkai has been my hobby since childhood.
Formal / Cultural context
江戸時代の絵師たちは、数多くの妖怪を絵巻物に描き残した。
Edo jidai no eshi-tachi wa, kazuooku no youkai wo emakimono ni egaki nokoshita.
Painters of the Edo period recorded countless youkai in illustrated scrolls.
Youkai grew out of attempts to explain the unexplained: a sudden chill, a missing child, a strange sound in the night. Each region of Japan developed its own creatures tied to local landscapes, so mountain villages, fishing towns, and city alleys all produced different beings. Edo-period artists and writers catalogued them enthusiastically, and works like illustrated youkai scrolls turned this folklore into a shared visual vocabulary.
Far from fading, youkai remain a living part of Japanese popular culture. Manga, games, and animated films constantly revive old creatures and invent new ones, and towns associated with famous folklore turn their local 妖怪 into mascots and tourist draws. This blend of genuine tradition and playful reinvention is why the word feels both ancient and thoroughly contemporary.