In "Choque: The Untold Story of Jiu-Jitsu in Brazil Vol. 2 1950-1960" by Roberto Pedreira the author makes numerous references to the large Japanese immigrant colony that came to Brazil pre-WW2 refusing to believe that Japan lost the war. A quote is below.
This book is mostly translations of Brazilian newspaper articles and is heavily cited, however this claim about the Japanese is not.
Was there a significant denial of defeat among the Japanese diaspora?
"In the jungles and plantations of Brazil, most Japanese people believed they had won World War II, defeating not only the Untied States ... but Brazil as well."
Edit: fixed obvious won/lost switch
Yes, there was a significant denial.
Most Japanese immigrants in Brazil didn't know how to read or write Portuguese (lots of them couldn't even speak Portuguese). They mostly lived segregated in their own communities, small villages in which most people were Japanese, or their own ethnic neighborhoods in towns.
During the Vargas dictatorship (1937-1945) Brazilian nationalism was on the rise and communities that didn't integrate with the rest of Brazil (like Germans or Japanese) were regarded with suspicion. This increased a lot after Brazil entered World War 2 in 1942. Japanese newspapers and Japanese schools were forbidden and even speaking Japanese in public was outlawed. This led to the Japanese community being isolated from news from the outside world, especially in isolated villages and farms in which 100% of the population was Japanese.
Some Japanese didn't think Japan could be defeated at all in a war. This belief was due to the kami kaze, hurricanes that saved Japan from the mongol invasion twice in the 13th century. This kind of nationalistic zeal increased in the Japanese Brazilian community as they perceived the Brazilians as mistreating them with their prohibition on Japanese newspapers and Japanese schools (school is a very important thing to Japanese in general, and to Japanese Brazilians as well). Most Japanese Brazilians at that time still thought of themselves as Japanese and that they would return to Japan after making some money in Brazil. They wanted to be seem as loyal subjects of the Empire, especially when they returned, so people avoided even thinking that the Empire could be defeated.
At this time, some Japanese Brazilians even formed terrorist groups to sabotage the Brazilian war effort. Most of their actions was basically sabotaging what Japanese Brazilians produced that could be used for war, like silk. The most infamous of this group was the Shindo Renmei (League of the Way of the Emperor's Subjects) which threatened any Japanese Brazilian who admitted Japan could be defeated.
As WW2 drew to a close, newspapers, radio transmissions and magazines came showing that Japan had been defeated. This caused a divide in the Japanese Brazilian community. Some believed in this evidence. They were called makegumi (defeatists), or more pejorativelly "dirty hearts". The ones who believed these were all fabrications were called kachigumi (victorious). In 1945 and early 1946 the kachigumi were the majority. I don't have the source at hand, but I think it was the IBGE (Brazil's official statistics office) publication for 100 years of Japanese immigration which states that in early 1946 85% of Japanese Brazilians were kachigumi with the rest being makegumi.
The Shindo Renmei then starts to terrorize even more the makegumi, and ends up killing those who said that Japan had been defeated. 23 Japanese Brazilians were killed, with 147 injured in lots of terrorists attacks. In Bastos, a city in Sao Paulo, even one non-Japanese Brazilian was killed (a police officer) for meddling in the affairs of the community. The result was the arrest of tens of thousands of Japanese Brazilians, and some of them were condemned to deportation to Japan. From what I've gathered, not many of them actually made the trip, and lots of them were pardoned eventually (those that didn't admit towards murder).
In 1947 the evidence was too big and most Japanese Brazilians finally realized Japan had been defeated. Still, I heard the tale that some didn't believe that (then) Crown Prince Akihito was the real Crown Prince when he visited Brazil in the early 1950s. But this is just a rumor that I heard. I never actually met these people or saw one of them give a testimony at that date.
Most of the sources for this are in Portuguese, but there are some in English:
https://en.wikipedia.org/wiki/Shindo_Renmei
A Brazilian movie in 2011 kind of depicts these events, in a fictionalized way. It's called Dirty Hearts, and is based on the 2000 book of the same name. Most of the Japanese speaking actors are actually Japanese.