It is believed that temperate coral populations serve as refuge species and are likely to harbor unique lineages. This research examined the transcriptomic reactions of the temperate coral Acropora hyacinthus, collected from Nishidomari, Kochi, Japan in October 2018, when subjected to thermal stress. Coral fragments were subjected to a gradual temperature rise from 26 to 31.5 C, and then returned to 26C over a span of 23 days. Following the acclimation, bleaching, and recovery phases, the transcriptomes of the coral fragments were studied, along with fundamental physiological parameters such as pulse amplitude fluorometry readings, symbiodiniaceae population density, and chlorophyll a levels. mRNA is sequenced from total RNA collected from coral fragments subjected to an aquarium stress experiment. Coral fragments may contain genetic material from holobiont components such as Symbiodiniaceae.