Katsumi was exposed to the A-bomb while sitting on the veranda of his house, 1.3 kilometers west of the hypocenter. He recalls the moment when the outside world suddenly went dark. Although the house was destroyed, he was fortunate to escape without injury or burns.
In an attempt to escape the fires that were rapidly spreading toward his home from the hypocenter, he was unable to rescue his 14-year-old sister, who had been trapped under the collapsed house, and had to leave her behind as he fled.
He remembers seeing railroad tie beams burning on a railway bridge as he evacuated.
His 18-year-old sister, who was 1.7 kilometers east of the hypocenter, passed away two weeks later due to radiation exposure.
Currently, Katsumi is actively involved in peace advocacy, sharing his experience as a Hibakusha with students in elementary and junior high schools. He also serves as a member in the Hibakusha organizations of Hyogo Prefecture and Kakogawa City, participating in movements to eliminate nuclear weapons.