Two half-brothers try to cope with the loss of their father.
Sadao and his younger brother, Kousaku, are promised a day at the beach by their father. But while they are at school, their father has a heart attack and dies. Their father's friend, Okazaki, comes to visit the widow. it is revealed that Sadao is actually the son from an earlier marriage. Sadao does not know, and the two agree that he should not be told.
Years later, Sadao finds out when he is applying to college that he is not his mother's biological son. He is angry that he was never told, but Okazaki chastises him and he swallows his hurt feelings.
Kousaku joins him in college where Sadao looks after him. One day at home, they and their mother are visited by Okazaki's widow, who give them an oar that her husband treasured. It is from their college days when both he and their father crewed together.
At school, Kousaku is less studious, and is more interested in taking a trip (and to see a girl.) than studying. Sadao tells him he can as long as their mother agrees. At home, Sadao borrows some money from hi mother, telling her it's fora friend, but he gives it to Koussaku for his trip. Koussaku refuses because their mother is having financial difficulties. Sadao is resentful. Why is she treating him differently? He does not feel that he is treated equally. His resentment grows, and. eventually, he breaks off with his mother and his brother. Kousaku tries to fight with him, but Sadao refuses to return the blows. When Kousaku comes home, his mother finally reveals to him that Sadao is not her natural son. He vows to go after Kousaku, but it is the mother who confronts him at a brothel where he is staying. He does not relent. He tells her that he never wants to see her again. After she walks away forlornly, an older woman who works there, speaks with him about her own son. Sadao is moved by her story, and returns to his mother to apologize.
