It depends on how you live. If you want to go there, work at a Japanese company, and then attempt to be accepted by Japanese people then you will have a hard time.
I lived there for a few weeks to a few months at a time over the years and find that I enjoy "living there" because my income and my social life aren't reliant to conforming to Japanese society. As a result, I enjoy learning about all the cultural quirks and learning the complicated language.
Another question you should ask if Japan is a good place to live in general. The answer is it depends. If you like a clean country where people are polite, crime is low, and food/air/water quality is amazing, then Japan is great. If you care about making new personal connections, then it is not.
Japan ranked 3rd lowest in a recent survey asking people in 30 countries "are you happy?"
TOKYO -- Only 57 percent of Japanese people feel they are happy, the third lowest rate among 30 countries surveyed, a report by French public opinion
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They were dead last when it comes to satisfaction with jobs, friends, and finances. The culture that leads to cleanliness, meticulous attention to detail, and efficiency in city living also promotes a sense of impersonality and stifling desperation. This is pretty obvious if you spend time walking around Tokyo around rush hour and try to find a happy smiling face among the sea of stressed, exhausted, or zoned out ones.
My advice is to live in a country with good economic opportunities and where you can develop good social connections. Travel a lot and figure out what you like and don't like about different cultures. After that you'll be immune to social conformity and be able to develop your personality according to what makes you happy rather than what people expect of you.
Japan is an amazing place in many ways. And I'll be coming back to live or visit often. But I'm very glad I never moved there after law school like I wanted to. I'm almost certain I'd be a more anxious and unhappy person if I did.