Kaupichthys japonicus is an eel in the family Chlopsidae. It was described by Kiyomatsu Matsubara and Hirotoshi Asano in 1960. It was originally a subspecies of Kaupichthys diodontus (the common false moray). It is a tropical, marine eel which is known from Japan (from which its specific epithet is derived) and the South China Sea, in the western Pacific Ocean. Males can reach a maximum total length of 23.8 cm. K. japonicus spawns in the summer.