Ocean acidification is one of the problems of global warming. In order to investigate the state of ocean acidification in Japan’s coastal areas and its impacts on coastal organisms, the Ocean Acidification Adaptation Project was launched in 2020 on a grant from The Nippon Foundation. The two-year study has already begun to provide insight into the causes and effects of acidification, and it’s becoming clear that technology used for improving coastal water quality is useful for limiting acidification. We are anticipating effective measures for adapting to acidification in Japan’s coastal regions.