Abstract
Based on the first record from Japanese waters, we describe the external features of the rarely encountered echinoid Sinaechinocyamus mai. Morphological characteristics of denuded test specimens, found washed ashore at Oshima County, Kagoshima Prefecture in 2025, were consistent with previous descriptions. This discovery extends the northernmost distributional range of this species in the Pacific Ocean. A new Japanese standard name for this species, Namidanoshizuku-kashipan, is proposed.
