In Hiroshima in 1945, an American prisoner of war and a Japanese nursing student grow close and become lovers, only for the atomic bombing to separate them. The animated film draws on the books of historian Shigeaki Mori, himself a survivor of the bombing, who spent more than four decades researching the twelve American bomber crew members and prisoners of war who died in the blast. Director Jimmy Murakami, once held at the Tule Lake internment camp during World War II, hoped to make his final work about Hiroshima, and the project grew from that wish. The title takes its name from the Irish folk song The Last Rose of Summer.