Germany hosted the games in 1936, WW2 ended in 1945 and the first Olympics after the war was only 3 years later in 1948 in Switzerland.
Was Germany and/or Japan invited to those games? Did they attend and if so, what kind of reaction did they get from the audience? 3 years is definitely not a long time after such a destructive war and the wounds that people suffered were probably still very fresh. What was that time like?
The 1948 Olympics were held in London and Germany and Japan were not invited to participate as a result of their role as aggressors.
From the wiki about the 1952 winter olympics:
In the aftermath of the German occupation of Norway during World War II, anti-German sentiment began to affect preparations for the 1952 Olympics.[17] Discussions were held to consider whether Germany should be allowed to participate in the Games.[18] When in 1950, the West German Olympic Committee requested recognition by the IOC, it raised the question of whether their participation would cause political boycotts in the upcoming Games.[19] Once the IOC recognized the West German Olympic Committee, West Germany was then formally invited to compete at the 1952 Winter Games.[20] East Germany was invited to participate with West Germany, as a unified team, but they declined.[21]
At first Norway was reluctant to welcome German athletes and others considered Nazi sympathizers. For example, Norwegian speed skater Finn Hodt was not allowed to compete in the Norwegian speed skating team because he collaborated with the Nazis during the war.
Eventually, despite the concern, Norway agreed to allow German and Japanese athletes to compete.[18] The Soviet Union sent no athletes to Oslo, despite being recognized by the IOC. They had intended to enter a team in the ice hockey tournament, but applied too late to join the International Ice Hockey Federation.[22][23]