Note also that Japanese law implements blood citizenship and not birthright citizenship. Domestically born children of immigrants remain immigrants, in general.
Very notably not in the US, however. All persons born or naturalized in the United States and subject to the jurisdiction thereof, are citizens of the United States and of the State wherein they reside.
Because of our history of slavery and settler colonialism more generally. The circumstances differ because of our somewhat unique historical circumstances, although some European countries enacted similar measures for their former colonies.
Arudo Debito, who was born in America but became a Japanese citizen in the 1990s, wrote a detailed article comparing the two countries' naturalization processes:
>You can get residency semi-easily but getting citizenship is extremely hard.
As far as I can tell from the description of the procedures involved, it's actually easy - and certainly easier than the US, and it requires less time in the country to apply than some European countries. One reason why it's uncommon however could be because Japan does not allow dual citizenship, and it's harder to get into the country in the first place other than teaching English.
It is actually quite easy to become a Japanese citizen. I’d be interested to hear where you got the impression that it is difficult. It basically requires 5 years of legal residence, a steady job, mediocre language ability, and paying taxes properly. For many people, attaining citizenship is easier than permanent residency.
I've got family in Japan. All you need to do is to go to Japan to see that it's very "japanese".
You can get residency semi-easily but getting citizenship is extremely hard.
It's not the EU or the US where a huge lot of "foreigners" can become citizen.