Oe's A Personal Matter begins in an unspecified city in Japan where the lead character, Bird—who is referred to only by his childhood nickname—is awaiting the birth of his first child. Intent on using a trip to Africa to test his mettle and lay the groundwork for a book, Bird is not happy about the idea of becoming a father. The baby is born with a serious brain deformity and Bird learns that the boy faces life in a vegetative state, if he survives at all. Angered by his loss of freedom, Bird turns to alcohol and an old girlfriend, Himiko, whose husband committed suicide at a young age. After a long evening with Himiko, Bird arrives at his teaching position with a hangover. After he gets sick in front of his class, Bird departs, sure that he has lost the position his father-in-law helped him obtain. Bird visits the hospital, where he learns something that further unsettles him: his son has begun to gain strength.
Bird continues to see Himiko, who attempts to convince him that he is as blameless for his child's condition as she is for the death of her husband. Intent on escaping to Africa with Bird, she tries to convince him to remove the infant boy from the hospital, which will severely lessen the child's chance for survival. After he removes the baby from the hospital, however, Bird begins to have second thoughts about his decision. Driving through a rain storm with his screaming infant son, he begins to comprehend the depth of his selfishness.
Much to Bird's chagrin, Himiko reminds him that he once betrayed a friend, Kikuhiko. Perhaps inspired by the guilt he feels for having betrayed a close friend and his own son, Bird names the child Kikuhiko. After Bird and Himiko deposit the baby in the care of a doctor of questionable skills, they run into Kikuhiko. Still embittered by his betrayal, Kikuhiko blames Bird for the wrong turn his life has taken. The encounter leaves a deep impression on Bird, who realizes that he has spent his adult life shirking responsibility—in friendship, marriage, and now, fatherhood. He sets out alone to retrieve the infant.
By the story's end, Bird has returned to his wife and child. Although the child was originally diagnosed with a hopeless condition, doctors begin to suspect that he is afflicted with an operable tumor. The operation requires Bird to donate blood. Finally willing to accept responsibility and with an infant son who might have a normal life, Bird prepares to pay for the operation with the money he had saved for his personal pursuits. No longer driven by the desire to test himself in Africa (where his former mistress has fled), Bird is content to work as a guide for foreign tourists to support his wife and child.