Hermissenda emurai is a species of brightly coloured sea slug or nudibranch, a marine gastropod mollusc in the family Facelinidae.

[2] This nudibranch was described from Niigata, Niigata Prefecture, Sea of Japan, Japan.

[1] Its distribution includes Korea[3] and the Russian coast of the Japan Sea (although, no facts confirming distribution in Russia provided).

It was (incorrectly) synonymised with Hermissenda crassicornis in 1983.

[4][2] The species grows to be about 50 mm, or about 2 inches.