SB: YōSEI/JAPANESE FAIRY DEFINITION
Yōsei (Japanese: 妖精, lit. "bewitching spirit") is a Japanese word that is generally synonymous with the English term fairy (フェアリー). Today, this word usually refers to spirits from Western legends, but occasionally it may also denote a creature from native Japanese folklore. For example, according to an old folk belief from Iwate Prefecture, it was once feared that the yōsei could bring the dead back to life. It is also mentioned that the people of Mt. Hōrai are small fairies that have no knowledge of great evil, and so their hearts never grow old.
The house spirits Zashiki warashi, are described as being the size of a five- or six-year-old child and prone to playing harmless pranks and occasionally causing mischief.
from Daijirin Dictionary.
by Akira Matsumura