Much of the story is told following the actions of Noboru Kuroda, an adolescent boy living in Yokohama, Japan. He and his group of friends are good students but they are secretly a gang. They don't believe in conventional morality and are led by their schoolmate, the "chief". Noboru discovers in his chest of drawers a secret peephole into his widowed mother's bedroom and uses it to spy on her. Since Noboru has a keen interest in ships, his upper-class mother Fusako, who owns Rex, a European-style haute fashion clothing store, takes him to visit one near the end of the summer. There they meet Ryuji Tsukazaki, a sailor and second mate aboard the commercial steamer Rakuyo who has vague notions of a special honor awaiting him at sea. Ryuji has always remained distant from the land, but he has no real ties with the sea or other sailors. Ryuji and Fusako develop a romantic relationship, and their first night of sex is spied upon by Noboru, who watches through the peephole. As Noboru is watching his mother and the sailor, a ship’s horn sounds, which Ryuji turns towards. Noboru is elated, and believes he has witnessed the true order of the universe because Ryuji turns away from feeling and is drawn to the sea. He describes this as an “ineluctable circle of life”, (p. 13) in which Noboru sees himself unified with Fusako and Ryuji. However, the couple's second night together takes place at a hotel to Noboru's disappointment. The relationship continues even when Ryuji returns to sea.