While many of the Japanese soldiers were heavily indoctrinated in the absolute righteousness of waging a patriotic war against Japan's enemies as well as the infallibility of the Japanese Empire/Japanese nation/State Shinto/Japanese Emperor as institutions, there wasn't really a comparable level of radicalization on the individual level that's comparable to the Nazis.

For example, while there were horrible atrocities committed by various Japanese forces throughout Asia, very rarely were they intentionally used on a strategic level nor were they organized as a cohesive whole to, say for example, exterminate Chinese or even a subsection of Chinese people.

Japanese soldiers were taught to abhor the Chinese not simply because they were Chinese but because China was Japan's enemy and the Chinese were it's soldiers. When Chinese people lived under Japanese rule, their ethnicity didn't preclude the possibility of coexisting peacefully with them (though predictably, very few Japanese soldiers and civilians alike voiced many complaints when Japanese people were given much more preferential treatment than non-Japanese populace of the Empire).

They were taught and indoctrinated about Japanese exceptionalism and were imbued with the ideas that Japan was at once the very best of peoples/cultures/nations in Asia, but also had a duty (and right) to properly control/use/rule Asia. A large part of this stemmedfrom the influence of Chinese history and culture, specifically how the Chinese hegemony held this position as the most dominant and patronizing political body in Asia for centuries. Watching this great power be torn apart by civil strife, colonial exploitation, and war was also a perfect opportunity for Japanese interests, both pragmatically and ideologically/spiritually.

It was Japan's turn to be top dog.

As for soldiers' experiences from the war itself, a great many of those who survived would invariably end up going home with terrible war trauma, PTSD, survivors guilt, illnesses, disabilities, infirmities, and general mental distress. Many that were returning home had not seen Japan in years. A great many returned even later, especially if they were held as POWs by the Soviet forces.

When Japanese forces returned home, it was obviously a complicated situation.

Japan had been saturated with bombs to the point that the air campaign had begun to run out of serious strategic targets to hit.

This obviously had the effect of making living in Japan an incredibly grueling and horrific experience even if one was lucky enough to not be killed or injured in the bombings. Japan was also effectively on the edge of suffering widespread outbreaks of famine and disease because of both the air campaign and the stranglehold of the naval blockade.

Repatriating millions of Japanese soldiers, settlers, and civilians at a time like this was a logistical nightmare.

Before the occupation and national governments even thought about addressing individual mental/spiritual/ideological issues, they needed to address the questions of food, security, and shelter, in that order.

Once that was done, the task of dealing with the returned soldiers and still extant military command structure (as well as government officials) was handled by both the occupational gov and Japanese national gov.

Both had different aims and jurisdictions to carry things out.

For example, the occupation gov's main aim was to reduce the rampant militarism that had defined the Japanese military leadership as well as various political and economic blocks that had strongly advocated for aggressive imperialist conflicts. They also wanted to hold specific individuals responsible and try them for their apparent war crimes that would be internationally recognized.

Meanwhile, the national gov wanted to utilize the returning soldiers as bolsters to the rebuilding efforts, desperately needing manpower and talent to reorganize and restore the nation from its political and economic shambles.

The soldiers themselves were viewed in various lights by society. On one hand, they were the literal embodiment of the war and the horrors that the war had visited on them, as well as defeat. The soldiers had lost and failed. On the other hand, they were also loved ones, the patriotic sons, brothers and husbands that survived and made it home. Very often they were seen as much as victims as anyone else. With their return, many of Japan's families were repaired, if often not whole.

The political atmosphere was even tenser than the social atmosphere, if that were possible. Imperialist/Ultra nationalist factions were still in power, and many of the political voices that were silenced during the war were bounding back, including progressive/socialist/communist groups. And of course, the occupational forces and those who were politically aligned with them represented the democratic bloc. Religious groups that were co-opted by the wartime government were as fractious as any other groups, and economic factions sided with whoever they thought would best protect their interests. Not to mention the whirlpool of politics that surrounded the Emperor, the top decision makers of the wartime government, and the political clout of the military and those associated with the military.

While we know today that nothing tumultuous happened and the Occupation of Japan went relatively smoothly, really more smoothly than most thought it would be, it was not guaranteed to be so.

I think from the brief points that I covered alone, we can see that Japan was very unstable.

This was the kind of Japan that soldiers were returning to.

To keep a long story short, Japanese soldiers returned to a country that was no longer at war.

Many of these liberalizations, such as the return of some freedoms of press (with strict limits), lifts of various bans on activities and past times that were considered immoral, unpatriotic, or outright 'against Japanese values' (like jazz clubs), and the eventual political liberalization that would culminate in the modern Japanese democratic process changed many Japanese people.

The direct influx of foreign, particularly American ideas forcibly introduced via Occupation policies, also changed a great deal of Japanese people's ideas and values, soldiers or not. These were often not easy nor simple changes and soldiers were no exception.

Education was changed and there were programs that specifically targeted soldiers. Men that the authorities were worried about were watched and occasionally imprisoned. It's important to note that for a long while, the Occupation's biggest worries were the security threat that returning soldiers and military leadership posed. The national gov on the other hand mainly saw the returnees as a necessary and useful component of the reconstruction of Japan, radical ultranationalist imperialist or not.

To this end, 'radical' soldiers/officers that were deemed security threats were removed from positions and places where they could cause trouble.

Mass media, now relatively free compared to wartime censorship (though still under the heavy hand of Occupation censorship) as well as academia and publishers, were now free to criticize the Japanese government, the war, the military, the economic powerhouses that encouraged and profited from conflict, etc etc quickly drove popular opinion against both the war and those who were seen as the cause of the war.

A great many soldiers and military staff were persuaded, many seeing themselves as unwilling participants who had been victimized, like Japan as a whole, by the few who plotted to bring them into a terrible war.

But this would only last until the Cold War was in full swing

By the time the Occupation of Japan had ended, American interests had changed. They were no longer concerned about removing militarist and imperialist/ultranationalist officers, generals, politicians, and business leaders from power.

Now America was concerned with Communism.

And they wanted a strong ally that would stand against the Communist firestorm spreading across Asia.

Many militarist leaders and figures who were purged were reinstated, often in the same positions, other times in other places. These men were valued for their experience and their hate of Communists.

This is where the roots of residual radicalism in modern Japan come from.

Many of the seeds of radicalism that pop up later in the 80s and 90s can be traced back to the 50s and 60s when many of these radical people quietly return to power. Radically ultranationalists were no longer targeted and hated by the public. This is also about the time that the military is no longer demonized by the public but now remembered for their heroics and sacrifice.

This is also about the period where war criminals were first considered to be enshrined at Yasukuni Shrine. In the years directly after the end of World War II, the Japanese governments themselves considered all convicted war criminals to be criminals in Japanese law as well, and those who were executed were not considered to have died while in service to the state.

It was only decades later when this view slowly began to change, first with recognizing that war criminals were indeed servants of the Japanese state, and culminating years later in their enshrinement at Yasukuni with all the other war dead.

To sum it up, this is a very long and complicated topic and I would love to answer specifics but it is quite a huge question to tackle in the space of an hour.

Please feel free to ask more questions about specific things you'd like to know!