She survived an atomic bomb. Now she campaigns against them.

Setsuko Thurlow can’t give her testimony without feeling some amount of pain. Telling her story involves reliving memories of fear and shock, losing loved ones and nearly her life. But it’s also the only thing she can do to honor those who died. Giving her testimony is hard, she says, but she feels she has no choice. It is her “moral obligation” to tell it.

Ms. Thurlow is a hibakusha, an atomic bomb survivor. More than a mile outside Hiroshima, Japan, when the first atomic bomb was dropped on the city, she survived without major injuries but would never be the same. She didn’t know it then, but telling that story would become her life’s purpose.

An activist for decades,