4 ideas
The narrator, grieving the wife he lost the year before, buys summer flowers and lays them on her grave two days before 6 August 1945. On the morning of the bombing he is in the privy of his family house in Hiroshima, and the walls around him are what save him. He walks out through the collapsed city to the riverbank, where he spends the night among burned, swollen people begging for water and dying around him.
In the first hours after the bomb, the narrator realizes he must write down what he is seeing, and he carries a notebook through the ruins. It becomes a debt, and it can only be paid by accurate witness to those who did not survive. The testimony exists because the witness treats his continued life as borrowed for that purpose.
Faced with the scorched landscape, the poet switches to a fragment written in angular katakana instead of flowing, lyrical script. He does this because the scene has a hard, geometric, inhuman quality that ordinary poetic diction would soften into beauty. The form of the writing itself signals that the event lies outside the range of human expression.
The account is told in a plain, almost affectless run of concrete details: a dead horse, a stranger's burned face, a boy identified only by his belt. The restraint lets the reader supply the horror the narrator cannot yet feel, and that makes the horror heavier.