The hydrothermal vent crab Gandalfus yunohana is found along the Izu-Ogasawara Arc in the north-western Pacific at depths from 420 to 1400 m. To study the larval developmental characteristics of this vent endemic species, we collected adult crabs from a depth of 445 m in May 2005 from the Kaikata Seamount (26°42.607′N, 141°04.457′E). These individuals were maintained at atmospheric pressure and temperature (15 and 18°C) for several months, until two females spawned and released larvae. Larvae were maintained at atmospheric pressure and at five different temperatures ranging from ∼18 to 30°C and fed Artemia sp. At ∼18°C, no larvae survived until the second zoeal stage. Some larvae reached the second or third zoeal stages when reared at ∼21°C. At 24-30°C, six individuals metamorphosed into the megalopal stage following a fifth or sixth zoeal stage 34-60 d after hatching. Megalopae swam actively, but they eventually died 58-104 d after hatching and showed no signs of moulting into the juvenile crab stage. Newly hatched first stage zoeae were phototactic, and we observed relatively high temperature requirements for larval survival and development. These facts suggest that zoeae may be distributed relatively high in the water column in warmer near-surface waters during their planktotrophic development. This is the first report of successful larval rearing of any species of bythograeid crabs. Our study establishes the conditions under which the megalopae moult to the first crab stage, laying the groundwork for future experiments.