We conducted a biosurvey in the mesophotic zone of Oura Bay, Nago, on the east coast of Okinawa Island, the Ryukyus, Japan, since fauna in this zone is not well been known. We found the sea pen species Calibelemnon hinoenma Kushida & Reimer (Cnidaria: Anthozoa: Octocorallia: Scleralcyonacea: Pennatuloidea: Scleroptilidae) on the sand and mud sea bottom of this bay at 55-60 m depth. This is the first report of this sea pen from the east coast of Okinawa Island and the second report after its discovery in Amami Oshima and from the west coast of Okinawa Island. This report strongly suggests that Oura Bay has unique fauna in the mesophotic zone in addition to previously found rare organisms in the shallower waters.