noun
A small, mischievous supernatural creature from Japanese folklore, similar to a Western imp or goblin. Often depicted as a minor oni.
昔話には、よく小鬼が登場する。
Imps often appear in old folktales.
その小鬼はいたずら好きで、村人を困らせた。
That imp was mischievous and troubled the villagers.
Compound of 小 (ko, 'small') and 鬼 (oni, 'demon, ogre'). The reading こおに is a straightforward combination of the kun'yomi readings of the two kanji.