We conducted a survey of coral diseases at two sites at Akajima, Kerama islands, Okinawa, Japan in 2010 and 2011. Diseased colonies recorded in both years were categorized into four types, namely, Black Band Disease (BBD), Skeleton Eroding Band (SEB), Growth Anomalies (GA) and White Syndrome (WS), and BBD on encrusting Montipora spp. was the dominant disease. We therefore focused on the BBD on Montipora spp. and analyzed the distribution of BBD-diseased colonies and the progression of BBD bands. Results revealed that the BBD distribution showed significant small-scale clustering in both years. The progressive band showed four morphological patterns on the same individual, and the composition of band patterns changed throughout the observation periods. The maximum progression rates were approximately 3 to 5 fold greater than the minimum rate at the same sites and times. These results suggest that BBD-diseased colonies at Akajima are aggregated and show different responses to factors related to BBD progression, even at the single-reef scale.