The story takes place in a beautiful ocean. There is a huge resort development project ongoing there. Nagisa Umi (played by Satomi Ishihara) is a distinguished researcher at the Marine Science Research Institute affiliated with Shibaura Institute of Technology. She loves fish and enjoys using seafood as a metaphor for any topic. She is cheerful, loves to laugh, has a good sociable personality, and treats everyone equally, but she is reluctant to talk about her family and past. She laments the pollution of the ocean caused by plastic waste and feels a sense of mission to prevent the resort development. She has the ability to communicate with marine life, and one day, Umi meets a man named Rentaro Nitta (played by Go Ayano). Rentaro comes from a wealthy business family but chose to work for an overseas IT company. However, as his father's health deteriorates while managing the family business, Rentaro, as the heir to the family enterprise, has no choice but to leave the company and return to Japan to take charge of a large-scale development plan. One is Umi, who opposes the resort development, and the other is Rentaro, who wants to promote the development plan. Although they have different identities and positions, they gradually become attracted to each other. This is an environmentally-themed story that explores points of agreement amid conflict, as well as a romantic fantasy tale about overcoming all obstacles to ultimately find happiness.