Title. To put it simply, I often get conflicting answers, from the atomic bomb to the Emperor buying into Truman's bluff, to the Soviet invasion of Manchuria. I was hoping to get a somewhat straight answer on the main cause on Japan surrendering. I would also like to know if this is debated in the academic world,or is it like the south fought to preserve slavery, where most historians agree on the facts and the debate is exclusively for political reasons.
This question comes up quite a bit here, probably because there is no consensus. /u/quiaudetvincet has a good answer here and searching the subreddit for "Japan surrender" also returns several other worthwhile answers. You can also find some similar questions in the FAQ and three older answers linked by /u/jschooltiger here.
Some well-respected historians believe that the atomic bomb was the primary factor, while others who are equally as qualified believe the Soviet Union's entry into the war was the primary factor. Others argue that the twin shock of both events happening in such a short period led to the decision.
Most everyone agrees that Japan had been seeking a negotiated surrender with the Soviets as intermediaries in summer of 1945, but only with specific terms. Even after the Soviets entered the war (with only a few hours notice) and the two atomic bombs were dropped, the Supreme War Council was divided on whether to continue fighting or not. It was a close decision, and thus it may never be possible to determine if one event had a larger impact than the other.