"I can’t forget it. The sounds of B-29 bombers and the images of mangled-up people come into my dream sometimes," Tsuiki said. His audience has spread to other countries. "As long as I’m alive, I want to talk not only to Japanese people but to everyone around the world."

Seventy-five years ago, Tsuiki was attending a teacher training school in Nagasaki. As Japan struggled in World War II, he was mobilized to work at a weapon production factory. On the morning of August 9, he was sleeping at a dormitory after a night shift.

Tsuiki: "The sound of the dorm collapsing woke me up."

The atomic bomb destroyed the two-story wooden structure located 1.8 kilometers from ground zero. Tsuiki’s room was the only one that barely survived. He rushed outside and saw many injured people in a nearby trench.

Tsuiki: "My neighbors were disfigured in the face and other parts of their body. Some had no eyes. Some carried their dead child. In a month or two, people in the neighborhood began dying one after another. That was shocking. I thought I’d be the next to go."

Tsuiki had symptoms of radiation sickness like fever and diarrhea for about three months. He eventually recovered and became a math teacher in 1947 at age 20. Several years passed before he learned details of the atomic bomb.

Tsuiki: "I saw pictures for the first time and realized the true horror of the situation. I bought photo books and other resources to study about the atomic bomb. Combining that with my experience, I felt I had to hand down my story."

Tsuiki stresses the importance of peace education at schools. In 1983, he began storytelling as a member of the Nagasaki Foundation for the Promotion of Peace. The group aims to eliminate nuclear weapons and achieve permanent world peace. He has given more than 1,000 lectures since.

After retiring as a teacher, he expanded his activities overseas. But he soon stumbled on an obstacle. "As I was giving talks, I wondered if my emotions were actually getting across," he wondered. He decided to tell his story without the help of an interpreter.

Two years ago, he gave his first speech in English. The foundation has suspended storytelling events for the time being due to the coronavirus. Tsuiki is using the time to practice English every day. He is working on overcoming the language barrier to share his experience in the hope that the tragedy of war that he witnessed will never be repeated.

"If we ever use it (a nuclear weapon) again, it will truly be the end of the Earth. Don’t ever forget that,” Tsuiki warns. "I want to stay healthy even after I become 100 years old. I don’t want to waste any time in telling my story to the world."