The memoir of a man who survived the horrors of Hiroshima is to be published for the first time this summer after its discovery in a US archive.

The 230-page memoir was written almost 80 years ago by Kiyoshi Tanimoto, who witnessed the city’s destruction after the atomic bomb was dropped in 1945. He will now be portrayed in a major feature film by Takehiro Hira, whose acclaimed roles include the detective in the Netflix Japanese-British drama Giri/Haji. Pre-production begins in November, ahead of the shoot in February 2027.

It is being made by Donald Rosenfeld, a former president of Merchant Ivory Productions, whose period classics include Howards End, starring Emma Thompson.

Rosenfeld told the Guardian that, with today’s impending nuclear threats, a film about Hiroshima and the publication of a survivor’s account could not be more timely.

“It’s an in-depth look at what this terrible bomb did,” he said. “It is so topical now with the Iran situation and North Korea. You can’t imagine anything worse than Hiroshima, but it could be worse – supposedly 10,000 times stronger today. We really have to make sure it doesn’t happen again.”

On 6 August 1945, the US attacked Hiroshima with an atomic bomb in an attempt to end the second world war. The world’s first nuclear attack decimated the city, reducing it to rubble. An estimated 120,000 people were killed within the first four days after the blast. Bodies were burned and disfigured through acute exposure to radiation. Three days later, the Americans dropped a plutonium bomb on Nagasaki, killing about 73,000 people. On 15 August, Japan surrendered, bringing an end to the war.

Tanimoto, who died in 1986 aged 77, was a Hiroshima Methodist priest, whose life was spared because he happened to be away that day, transporting a wardrobe to another town.

He returned to find unimaginable horrors. Having thought they could never be put into words, he eventually decided that a memoir “would help ensure that no one experienced it ever again”, his daughter Koko Tanimoto Kondo said.

In the memoir’s foreword, Kondo writes of the need for future generations to remember it as “memory is our hope for survival as human beings”.

Having lain unpublished and forgotten in a US archive, the memoir will be published on 6 August, Hiroshima’s anniversary, by Random House in the US and Penguin worldwide. The book has already been sold in most major territories.

Rosenfeld described it as “beautifully written”.

The memoir will be released by publishers worldwide this summer, with a 9,000-word foreword by Kondo, now 81. She writes: “For many years I could not live in Hiroshima, the city of my birth. On the day the atomic bomb dropped I was eight months old, a baby in the arms of my mother. It was 40 years before she could bring herself to tell me, in her own words, how I had survived. Few people would talk about that time. Their memories kept them quiet.”