The Japanese murrelet or crested murrelet (Synthliboramphus wumizusume) is a small bird that inhabits rocky islets and reefs in the warm waters of Japan, Russia and South Korea. It has black and bluish grey upper body and white underparts plumage.

Breeding sites are crevices, burrows and hollows in rocks, the gaps in piles of stones, and among grasses on uninhabited islands. The northern limit of the breeding sites are the Nanatsujima Islands of Japan, while the most important breeding sites are Biro Island and the Izu Islands.