Japanese version of The United Nations Decade of Ocean Science for Sustainable Development (2021-2030): Implementation Plan is now available from websites of the Ministry of Education, Culture, Sports, Science and Technology (MEXT) and of UNESCO as shown below.
ユネスコの科学分野における我が国の協力 (MEXT website, Japanese only)
持続可能な開発のための 国連海洋科学の10年 (2021-2030 年) : 実施計画 – UNESCO Digital Library (UNESCO website)