In an on-going faunal study of deep regions of the East China Sea, using a Remotely-Operated Vehicle (ROV), a single specimen (57.4 mm in standard length: SL) of Epigonus elongatus Parin and Abramov, 1986 was collected at 410 m depth off the west coast of Okinawa Island, Japan. The species has been previously reported only from the type locality in the Farquhar Islands, Western Indian Ocean, the present report being the first of the species from waters adjacent to Japan. The new standard Japanese name “Kogeme-yasemutsu” is proposed for the species, which belongs to the E. pandionis group, and is characterized by the following combination of characters: dorsal-fin rays VII-I, 10; pectoral-fin rays 18–20; gill rakers 22 or 23; vertebrae 10 + 15; pyloric caeca 7–9; pored lateral-line scales 48–50 + 2; pungent opercular spine absent; maxillary mustache-like process absent; lingual teeth absent; a pair of ribs on last abdominal vertebra absent; tubercle on inner symphysis of lower jaw absent; orbital diameter 12.1–13.6% SL; lowerjaw length 13.4–15.1% SL; and body depth 16.4–18.5% SL. An in-situ ROV photograph of E. elongatus from Okinawa Island is provided. The genus Epigonus is represented in Japanese waters by six species including E. elongatus; Epigonus atherinoides (Gilbert, 1905); Epigonus ctenolepis Mochizuki and Shirakihara, 1983; Epigonus denticulatus Dieuzeide, 1950; Epigonus fragilis (Jordan and Jordan, 1922); and Epigonus pectinifer Mayer, 1974.