[4] The Japanese murrelet is a monotypic species first described by Coenraad Temminck, as Uria wumizusume, in the text accompanying an 1836 livraison in the ongoing series Nouveau recueil de planches coloriées d'oiseaux.

[2][6]: 46 [7] The following year, Johann Friedrich von Brandt erected the genus Brachyramphus and subgenus Synthliboramphus, transferring to it the Japanese murrelet, to which he gave the new specific name temminckii.

[7] It may be distinguished from the Ancient murrelet (Synthliboramphus antiquus), which also occurs in much of its range, in particular by its summer crest of black feathers 3–5 cm (1.2–2.0 in) in length,[12] although this again is absent in winter.

[7][10] The Japanese murrelet's diet mostly comprises krill, other planktonic crustaceans, crangonid shimps, larval and small pelagic fish, including Pacific herring (Clupea pallasii), sculpin (Triglops), and smelt (Osmerus), sand eels (Ammodytes), and sandlances (Hypoptychus dybowskii).

[12] Typically two eggs are laid, a week apart, from late March to early April, though this takes place a little earlier on Tori-shima, at the southern end of its breeding range.

),[16] feral cats (Felis catus), large-billed crows (Corvus macrorhynchos),[13] and black-tailed gulls (Larus crassirostris),[13] and, to a lesser extent, the ongoing danger from pollution, gives the Japanese murrelet its Vulnerable status on the IUCN Red List.