I am living in Japan (Tokyo and after retirement in Okayama) since 45 years. Originally from Austria (EU).
It is great that you passed JLPT1 - I think without extensive exercise I will not pass it now, but many years ago I passed various technical exams in Japanese, also passed in a public university Japanese B (basic) and Japanese A (advanced) - it was something like JLPT 5 to 1, which did not exist at that time when I arrived. There was no computer test like now, just a pencil, a paper and a tape-recorder, all had to be written by hand...During my time in Japan, I learned the language to a high level (I passed JLPT level 1, although in recent years my level of Japanese language proficiency has gone down significantly due to disuse and language attrition) and I lived almost exclusively among Japanese people and other Asians (Chinese, Korean, Vietnamese, etc.), and I can say that life in Japan really isn't as great as some people like to make out.
Japan might not be as great as some people think about it, but if you compare Japan with all other ASIAN countries around it, it's still the best place in that region. It's relativ, compare Japan with which country in Asia?
Even comparing Japan with USA - At least Japan offers you as a foreigner (if you have a proper visa to live in Japan, except diplomats and tourists) a good health insurance system, a crime-low society and fully functioning public transport - you will not find this for example in USA.
This is true, Japanese people are not very communicative, not only against foreigners, but also among themselves.As you, myself and others have mentioned, Japan has high levels of social alienation, a brutal work culture, a high suicide rate (although not as high as those of South Korea and some of the former Soviet bloc countries), and a major incel problem and epidemic of loneliness.
You're right that most people other than anime nerds don't have much interest in Japan. At least that's how it is in my part of Europe......
Living in Japan permanently as a foreigner, you need to have a family - all these few people from my own native country (Austria, EU) who decided to live in Japan have Japanese family and found in Japan a regular job with reasonable income (often related to foreign companies) and also own their home and do not pay rent and are able to speak and read Japanese (otherwise you will feel to be an illiterate)
About 'brutal working culture' - in my case it was indeed a very irregular working time, I never could plan anything in advance - but working with an European related contract, I had in return as compensation not only fully paid overtime, but also the right for 6 full weeks paid vacation - so I could leave Japan 2 times a year for 3 weeks to another country - if you live as a foreigner in Japan, you have to get out of Japan from time to time.
I have another second home for holidays and now for retirement in Thailand, and sometimes I also visit Philippines, Malaysia, Cambodia etc. but I never came back to Europe.
About being interested in Japan, most foreigners living here are from nearby Asia - Chinese, Koreans, Filipinos and also Brazil-Japanese, Vietnamese...
You might add some US-military servicemen, but almost all of them are coming and leaving. The few people from Europe (like I myself) or from elsewhere who stay in Japan are a tiny group only.
Foreigners are mostly living in the large cities in Japan, same with me before, because where can you earn money for your daily life?
But Japan is not only the life in the big cities, which is often really difficult, with high rent, small rooms, crowded wherever you go, no nice green area nearby to relax, lot of traffic (but is this so much different from other Asian large cities?)
Most foreigners were never living anywhere else in Japan and think, all Japan is like Tokyo....
However after retirement we were moving out to a smaller city, and our home is outside of the city center - plenty of space, no parking problems, I have 2 cars and also a motorcycle, nice view to river and forests and hills and not far away from the sea... Very different from Tokyo.
Real estate prices are about 1/3 or 1/4 or even less compared to Tokyo, but of course, there is no job here for a foreigner, you need an income from somewhere else, like in my case, a good retirement allowance.
This is true, it was not always like that, and in Japan it is mostly a problem for the male population of any age, not only for young men.a major incel problem and epidemic of loneliness
The dating scene in Japan is not hateful or mistrusting - it cannot be compared with USA or UK. However there is now clearly a gender imbalance with more women in the large cities, with more men in the small cities and with almost no young women in rural areas.
The gender imbalance is not so bad if compared with China or India, but as far as I can see among young people (20 to 40 or so) it is around 15 %.
You can look for a foreign wife, and in Japan now there are many more Japanese men married with a foreign wife (usually from China, Korea, Philippines etc.) than Japanese women married with a foreign husband, outnumber them more than 2 vs. 1.