16S rRNA gene fragments from mesopelagic water collected in Nov 2013 at coastal area of Kumejima town, Okinawa, Japan (at a depth of 612 m) were analyzed to comprehensively reveal the bacterial community in a mesopelagic water mass (potentially North Pacific Intermediate Water) around Okinawa. The goal of this study was to comprehensively reveal the bacterial community in mesopelagic water masses around Japan for the first time. For comparison, 16S rRNA gene fragments from surface seawaters around Japan were similarly analyzed comprehensively for the first time.