Rivers play an important role in European culture. In Greek and Roman mythology, five rivers form the boundaries of the world of the dead. Among them, most notable are the Lethe river, which brings oblivion to those who drink from it, and the river Styx, separating the Underworld from the world of the living. The idea of rivers as thresholds between worlds is also present in Japanese mythology. After death, Japanese Buddhists believe that a soul must cross the Sanzu River in one of three places: a bridge, a ford, or a snake-infested stretch of deep water. The choice of a crossing place depends on how many sins a soul accumulated while alive. Across cultures, rivers are traditionally associated with death and crossing over to the afterlife.

In the novel, Etsuko’s interactions with Sachiko and especially with Mariko happen most often near the river. This connects all three characters to the idea of death. The infanticide witnessed by Sachiko and Mariko occurs in a canal, a man-made river, suggesting that such practice is a product of social pressures and expectations, rather than any individual or natural urges or desires.

During the novel, Etsuko crosses the wooden bridge twice, alluding to her close encounters with death during the Nagasaki bombing and the loss of her family, as well as a potential suicidal ideation.