We collected a total of four butterfly ray specimens (Gymnura japonica, 213.4-695.0 mm in total length) in Korea from 2016 to 2021 and investigated their morphological and molecular characteristics in order to clarify their taxonomic status. These features are summarized as follows. Disc lozenge-shaped, 1.8-2.0 times broader than long. Tail very short, post-cloaca length 23.9-28.2% in disc width. Snout short, no rostral cartilage. Clasper short, no hook. Dorsal surface uniform yellow or brownish grey, with or without rounded light yellow spots. An analysis of 434 base-pair sequences of mitochondrial DNA cytochrome c oxidase subunit I showed that all four specimens corresponded to G. japonica from Japan (Kimura-2-parameter distance = 0-0.2%), suggesting that the color patterns found may be due to intraspecific color variation. G. japonica resembles Gymnura poecilura but differs in that it has a shorter tail length to disc width (23.9-28.2% in G. japonica vs. 40.1-48.3% in G. poecilura). This study revealed that G. japonica occurred in areas affected by the Tsushima Warm Current, tentatively suggesting that G. japonica may be an indicator species for monitoring marine ecosystem changes due to climate change.