Eiji, a member of his school's swimming club, attends a high school on the mainland separated from his parents and family. For the summer the club decides to visit Sumire Island, Eiji's home town, for a mixture of training camp and vacation. Eiji is glad to see his mother again and meets lots of old friends and acquaintances.
However, in recent years Sumire Island has become a hot spot for summer tourists and is overcrowded, so the group has trouble finding a place to stay. Luckily, they all can stay at Eiji's place and even decide to start working as life guards, helping to protect the crowded beaches.