scr4–First off, don’t worry about professors and such telling you you’re not good enough to be in academia. I’ve found that those judgements aren’t exactly unbiased. It’s the very rare advisor who wants a student who could and/or would show them up in seminars, or outdo them in publications, or even whose research interests and/or aptitudes don’t fit exactly into the very precisely-defined openings in their labs. Also, it’s very easy for a professor–especially a prospective advisor you want to work with–to say, “you don’t fit in my lab/in this department” or “I don’t have an opening for you,” and have you hear, “You’re not good enough.”
Graduate school is a pretty ego-grinding experience. I think all of us, in any department, no matter how smart, talented, or hard-working we are, find ourselves thinking that we really suck at what we do. Heaven only knows I have. Some of us feel like that more than others, but there’s no-one who hasn’t had a moment of serious self-doubt. Don’t let the bastards–even the well-meaning ones–grind you down.
If you feel like you’re being told that you’re not good enough to be in academia, then maybe an academic career doesn’t suit you well. That’s not to say that you’re not good enough for an academic career–it’s just that you might be happier elsewhere. I know it’s hard not to take a pretty big hit to the self-esteem when you hear people telling you over and over again that you’re somehow substandard, but, really, the problem isn’t you; it’s them.
I’d bet there are lots of jobs you could have, with your PhD in astronomy. Or even without your PhD. You say you tend towards lab work. Well, what kind of lab work? Are you a whiz with optics? Lots of industries need smart, resourceful, creative people to design optics things for them and people really gifted in lab work to get those optics to do what they’re supposed to. Are you better with all the computer simulation/data analysis stuff? Believe me, that’ll get people interested in hiring you, too. IIRC, you love bikes, especially recumbent bikes. Could you work in designing and building custom bikes? I bet there are lots of skills you have that you don’t even realize you’ve got. Looking into those options might make you feel better, even if you don’t really move much towards any of them. I know that I often feel at my lowest about my life when I feel trapped, like I’m stuck with what I’m stuck with and have no other options. As you discuss the choices you have, and learn to make new opportunities for yourself, you’ll start to feel energetic and excited. You don’t have to stay in an environment that isn’t good for you, with people who don’t value what you have to offer.
Second–about the lack of female companionship thing. I’ve found that I can’t attract men when I’m unhappy. I just can’t. Mainly because, oddly enough, I’m unhappy, and no-one gravitates towards unhappiness. Maybe it would be best to put aside conscious efforts to meet women and concentrate on other things that make you happy. When you feel like your life in general is better, then you’ll probably find that women come to you.
As far as hating Japan–you could probably work anywhere in the world. Just start looking. Your campus career services might be able to help you with that. And, if they can’t, you might have a state employment bureau that can. I’d make a bet that, with your technical skills and abilities, you wouldn’t have to go to any country you didn’t want to.