I talked to a member of the Manhatten Project and a Japanese language historian.
The Manhatten Project member said he was there personally, Truman told off the scientists saying, "I don't want to show the fucking Japs a test. I don't care if they will surrender. They want to do a bombing, I'll show them a real bombing." The guy was crying like a baby telling me the story. He was ashamed of helping develop the bomb.
The language historian told me the emperor told Truman he humbly surrendered after the first bomb, but Truman took it as an insult and being mocked. Since you can translate honorific humble language from the emperor as mocking, since he never uses it. A honorable man would have found out if the surrender was sincere before doing a second bomb. Truman only cared about revenge.
Truman was a stupid piece of shit haberdasher. He was our worst president and a mass murderer.