Ive been to the Hiroshima atomic bomb museum and do not deny the suffering of ordinary the Japanese following the event however no where in the museum does it tell you what Japan had done during the war to cause the Allies to take the action they did.
When did you go? I've been several times, and there was a marked changed between early noughties and late noughties, co-inciding with the court case in Japan which finally acknowledged the large number of Korean slave labourers who had been affected, and then denied help by the Japanese government after the war. That flushed out a lot of the "poor innocent Japan, quietly going about its legitimate business of a near genocidal conflict prosecuted with great cruelty aiming at regional domination peaceably sewing kimonos and worshipping our ancestors, until the nasty Americans for no apparent reason spent a lot of money on building a cruel weapon which they used to finish a war which wasn't really happening anyway and even if it had been happening was a local war for local people, of no concern to outsiders" and more recently there has been talk of Nanking and Pearl Harbour, although not the Burma Railroad.
It's morally difficult. Germany had been, in some sense, a democracy up until 1933 and even though Hitler didn't broadcast the precise details of the Shoah, a lot of people knew and were perfectly happy to go along with it, and in many cases partake with enthusiasm. Letters from the camps written by guards, or from the Eizsatzgruppen on the Eastern front, were not censored, and it defies belief that people did not know. The films of allegedly unknowing German civilians being paraded through camps up the road from where they lived, affecting to be shocked by what had been happening are multi-dimensional bullshit: the myth of the "good German" who knew nothing suited everyone's purposes to construct, because even if those civilians didn't know the full horror and extent, they knew damned well that bad stuff was happening, but German post-1945 would have been ungovernable had that been pursued. Knowledge of the crimes was deemed not to be a crime, and probably in a nasty pragmatic way that was the right decision.
But in the case of Japan it had never been anything remotely approximating a democracy, and the vast majority of the population had no reason or way to know about the atrocities, which in any event were happening thousands of miles away. You can make an argument for the innocence of the adult population of Hiroshima which is much harder to make for the adult population of Hamburg; they genuinely didn't know what was being done in their name, nor would they have been able to do anything about it had they known.
The moral calculus is therefore not about the innocence or otherwise of the victims. The Atomic Bombs killed, in round numbers, including later casualties, no more than a quarter of a million people. At least a hundred thousand people a month were dying of starvation, ill-health and the effects of conventional bombing raids in early 1945, and that was set to accelerate: The 1945 rice harvest had failed, Operation Starvation had sunk over a million tonnes of coastal shipping and closed almost all the harbours, and the next step would have been tactical bombing, from carriers and nearby Islands, in the manner of the 1944 transportation plan in Europe, to sever all the railway and road bridges. In Japanese occupied territories the position was worse, and similar numbers were dying. Some estimates have the potential number of deaths from starvation in mainland Japan as high as seven million by the end of 1946, and it's likely that Operation Olympic couldn't have been launched until then.
So you get to choose, with your time machine. Say, a quarter of a million dead in August 1945, or twenty or more times that toll over the ensuing twelve months. Which is morally preferable?