As the novel opens, the narrator has been left on his own in Kamakura after his friend, who invited him to vacation there, is called home by his family. One day, after finishing his usual swim in the sea, he takes notice of a man in the changing house who's there with a foreign guest, preparing to head for the water. He sees the same man each day thereafter, though no longer with his foreign companion. After some days, he finds occasion to make the man's acquaintance. As they grow closer, he comes to refer to the man as “Sensei.”