A specimen (39.1 mm standard length) of the genus Ostorhinchus Lacepède, 1802, collected from Ishigaki-jima Island, the Ryukyu Archipelago, southern Japan, was identified as Ostorhinchus hartzfeldii (Bleeker, 1852). The specimen showed characteristic coloration of the species, including the following features: four slightly wavy longitudinal silver lines on the head and body, the dorsalmost running along the dorsal body margin to the caudal fin base, and the others terminating on the trunk or caudal peduncle; the entire body base color brown; all fins slightly reddish, transparent; a dark spot on the caudal fin base, of similar size to the pupil. Ostorhinchus hartzfeldii is similar to Ostorhinchus cookii (Macleay, 1881), Ostorhinchus nigrofasciatus (Lachner, 1953), and Ostorhinchus taeniophorus (Regan, 1908), but differs from them by having only the dorsalmost longitudinal silver line reaching the caudal fin base (vs. three or four lines reaching the fin base in the other three species) and absence of a longitudinal silver line on the ventrolateral aspect of the trunk (vs. present). Ostorhinchus hartzfeldii is distributed in the western Pacific, from the South China Sea to Australia, but had not previously been recorded from Japanese waters. A photographic record of the species from Ishigaki-jima Island is also included. The new standard Japanese name “Sazanami-ishimochi” is proposed, a reference to the slightly wavy silver lines that disappear with growth, based on the specimen collected from Ishigaki-jima Island.