The cyanobacteriosponge Terpios hoshinota encrusts living coral and other benthos, and occasionally undergoes massive outbreaks, resulting in large amounts of damage to coral reef ecosystems. At the same time, this species is theorized to be expanding its range in the northwestern Pacific. Despite this, the current distribution of this species in Japan is unknown, with no research having been conducted since an initial assessment in 1984-1985. To address this information deficiency, a survey of the Ryukyu Archipelago from Amami Oshima Island south to the Yaeyama Islands was conducted to assess the distribution of T. hoshinota over the period of 2009 to 2011. Field images have been posted as an online image archive for researchers to utilize in future research. Our findings show that the presence of T. hoshinota is not uncommon in this region, with at least 23 of 64 (=36%) sites with this species. This is a considerable increase from levels reported in 1984-1985 (11 of 182 sites, =6%), and suggests this species is now a permanent feature in the coral reef ecosystems of this region. However, large outbreaks were at approximately the same levels as reported in 1984-1985. Most T. hoshinota were found in shallow (<5 m) depths, and abundance does not appear to be greatly influenced by seasons. It may be that general degradation of reefs in these decades has contributed to the spread of this species. Long-term monitoring and additional research are needed to assess the threat T. hoshinota poses to the coral reefs of southern Japan.