OP comes off sounding wapanese.
However since you're in college, study abroad in Japan for a year. Then once you're there actually research what it means to live there, if you're wholly serious. I studied abroad there myself in college because I had similar interests (video games in my case), but ultimately what I learned was everything that >>12 summarizes:
Japan isn't a holy land with weird technological marvels where everyone knows and loves anime. Most of the college students I met didn't watch anime or read manga. They were typical college students, studying to make the grade with some extra cirricular activities that they enjoy, not too different from America. Most of them don't have time to play video games, in fact, I don't think I met anyone with a console. I think I met a few people with Nintendo DSes that they used to play stuff like Sudoku.
If you're interested in meeting people with similar interests, I think that you're best hope would actually be to stay in America and find other japanophiles/wapanese. If you want a girl that understands your anime hobby, you should go to things like Otacon, PAX, or like conventions in America to start meeting them. Trust me, you will find more friends and more girls with common interests going to those places than you would dumping yourself in Japan in the short term.
I also have a Japanese girlfriend (I met her on my study abroad), and can tell you that sustaining a long distance relationship to Japan is difficult. The plane tickets that we (her and I) buy in a year alone is about $2000-$3000, and that's not including dates, trips, and other things we do together. It requires a lot more budgeting than having a girlfriend in America I think. Trusting the other person is much harder when they are a good 5000 miles away as well. Is she that much ore different than girls I've met and dated in America? No, not really. Does she like anime, video games, or manga? No, not really. Do we love each other? Yes, very much. We have issues communicating, but as I'm semi-fluent in Japanese and am studying everyday to get better; the same with her and English, we're overcoming that hurdle slowly but surely. Just like American girls, Japanese girls will like you more if you can speak the language.
If you're interested in "work in Japan for foreigners," the outlook for me seemed pretty bleak. From what I saw, it seemed that (like >>12 mentions) the only jobs for foreigners are probably low-medium paying jobs like English tutor or teacher (JET/NOVA programs if you're so inclined). If you're a computer programmer, you might be able to find something at Microsoft or one of the other worldwide software giants and then transfer to a Japanese branch.
Take the above with a grain of salt, after all it's just my experience with the land of the rising sun and shouldn't be taken as anything other than that.