'In his memoir, he wrote of doubting his own senses when he first saw the devastation from two miles away: “The whole city was covered in dark clouds and conflagrations were breaking out in various directions … I was terribly afraid. It was then that black drops of rain, as big as raspberries, began to fall.”

https://www.theguardian.com/film/2023/sep/03/then-the-black-rain-fell-survivors-recollections-of-hiroshima-inspire-new-film