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Japan has a higher population density than the United States
Kyoto was the capital of Japan before Tokyo
"Kamikaze" was the family name of the first pilot who flew his plane into an enemy ship during WWII
The term Kamikaze, meaning "divine wind", comes from the typhoons which scattered the Mongol invasion forces thus protecting Japan
In Japanese religion, the Emperor is said to be the direct descendant of the sun goddess Amaterasu
Japan conquered about half of India during WWII
Baseball is the most popular spectator sport in Japan
Kimonos are worn by both men and women
Japan was conquered by the Mongols
They attempted twice, but failed both times
Hiroshima is today a radioactive ghost town
It is a thriving modern city
Christians were rarely persecuted during the Shogun rule
Japan has no territorial disputes with any country
Kuril Islands dispute with Russia is the most prominent
The Japanese stock market is still lower than its peak in 1989
It is possible to be Buddhist and Shinto at the same time
Godzilla needs to eat people to survive
He is powered by nuclear energy
Japan has a high degree of ethnic diversity relative to other countries
Nearly 100% of Japanese residents belong to the same ethnic group
Answer : Although widely promoted as "traditional japanese culture" by occidentals (especially Hollywood movies), "nyotaimori" is very uncommon in Japan, the only few occurences being illegal due to sanitary and ethical laws.
"There apparently was one nyotaimori establishment in Shinjuku's red light district during the late 1990s [...] It soon closed before health officials could shutter the establishment." (source)
They ware difficult questions.
Also, ethnicity depends a lot on how people identify themselves--if people feel they fit better with the dominant culture of Japan, they'll call themselves Japanese, even if they're partially descended from the Ainu or another minority group. This is common everywhere, but I'm guessing especially so in Japan, since it's a culture that values uniformity over diversity
Still, unlike many instances of overbearing brutality throughout history, the Tokugawas got the result they were looking for: Japan has very few Christians today. Unlike neighbouring Korea, for example, which has a serious infestation going; or China which got into the whole Taiping Rebellion situation.