Something of a racist lie has been propagated about Japan in order to justify the brutality - that they were fanatics (just look at the kamikaze pilots!) who would never surrender, who would blow themselves up rather than surrender. It was never true, and Japan had been seeking a way to surrender with terms for some time at the time of the A-bombs.
It's a form of dehumanising of the enemy, which always happens with wars, even down to 'the argies' in the Falklands. Read accounts of surviving kamikaze pilots, for instance, and you'll get a very different story, one of very young men, boys really, scared stiff, steeling themselves the best they could for the day they were called on, and desperately hoping that it would not happen. Regular humans, in other words.