From MangaHelpers:

Each chapter features a summer love story at a school in Kyuushuu. The first chapter focuses on Nao and Umi, who were friends as children. As they grew into teenagers, Nao became good-looking and popular with the girls, and Umi started to awkwardly avoid him as she began to feel her feelings towards him change. When they end up accidentally going on an excursion together, what confessions will come out? In the second chapter, a student develops a crush on her attractive new teacher, but struggles to deal with the fact that the feelings might not be mutual. In the third, Nana has a friendly and competitive relationship with the 1st-year Hikaru, who she plays basketball with. When they go to the summer festival together, will their friendly relationship become something more? [tethysdust]