Where does “тэнгу” come from?

тэнгу (Russian) comes from Japanese 天狗, from Middle Chinese 天狗.

тэнгу (Russian): tengu

Definitions

Step	Language	Word	Meaning
1	Japanese	天狗	a tengu, a mythical Japanese creature, typically...
2	Middle Chinese	天狗	—

тэнгу — Etymology, Origin & Word History | Etymology Explorer