The early part of the film recounts, in the style of a documentary, but narrated by the so far unidentified characters, the effects of the Hiroshima bomb on August 6, 1945, in particular the loss of hair and the complete anonymity of the remains of some victims. He had been conscripted into the Japanese army, and his family was in Hiroshima on that day.

The film uses highly structured, repetitive dialogue, mostly consisting of Her narration, with Him interjecting to say she is wrong, lying, confused, or to deny and contradict her statements with the film's famous line "You are not endowed with memory". Although He disagrees and rejects many of the things She says, he pursues her constantly. The film is peppered with dozens of brief flashbacks to Her life; as a youth, she was shamed and had her head shaved as shaming and punishment for having a love affair with a German soldier, which she juxtaposes with the loss of the hair "which the women of Hiroshima will find has fallen out in the morning."

Source : Wikipedia.