HIROSHIMA, Japan — The crowd sat entranced as 78-year-old Emiko Okada recalled the horrifying events of Aug. 6, 1945, a day that started hot and cloudless. There was the buzz of the plane, the huge flash, the cries for water, the kids like ghosts with skin dangling off them, the people with their guts hanging out.

“We don’t want you young generations to go through what I did.

You can help by spreading what you just heard from me to other people,” Okada – a hibakusha, or “atomic bombed person” – said this week in Hiroshima not far from the spot where American forces dropped Little Boy, the first atomic bomb to be used in warfare, 70 years ago Thursday.

Not only is Okada telling her own story, but she has also begun to train an apprentice to continue disseminating her tale after she’s gone: a memory keeper, one of a growing number here being designated as an “A-bomb legacy successor” as the number of survivors dwindle.

While there are still more than 183,000 survivors of Hiroshima or Nagasaki alive in Japan today, their average age is 80, according to official statistics.

Okada’s designated storyteller is a 39-year-old man who works in a Tokyo department store and has no direct ties to Hiroshima. But since visiting the peace museum here as a college student, the memory keeper, Yasukazu Narahara, has become almost as ardent as Okada when it comes to making sure their fellow Japanese do not forget how the bombing came about and the devastation that nuclear weapons cause.

Japanese children do not spend much time learning about World War II at school, with the official curriculum guidelines saying students should understand that the war “caused sufferings to all humanity at large.”

A recent poll by the public broadcaster NHK found that only 30 percent of adults could correctly give the date of the Hiroshima attack and even fewer knew when the Nagasaki attack happened.

“I hope I can build a relationship with her like a son” so that Okada will bequeath him her innermost thoughts, Narahara said after organizing the session at which Okada spoke.