Dear OP, I am currently in a LDR (Long Distance Relationship) with a beautiful and amazing woman in London. We have bean dating for nearly a year and we chat on skype as constantly as possible. What I believe can be done with someone in the same house, I believe can be done with someone across the world. The most important thing to a LDR is communication. Be sure to talk about everything you want to, then think of things you wouldn't want them to know and then talk about it if you find it pertinent. Share your hopes, dreams, likes, dislikes, how you like to get ready for bed, how you like your shower water, what you like on your pizza. Certainly you don't have to do this all in one conversation but the best thing you can do is to learn as much about each other as possible and just see if you fall in love with everything about her.
As for her living in Japan, make an effort to learn a lot about her culture, learn proper etiquette from her, talk about what ceremonies and festivals she's been a part of, Japan is a rich and beautiful place and there is so much to learn and love about just the country itself. Then you want to plan to get there, in the first 6 months you need to make a plan for the first visit or be thinking about a move. Talk about who would move where and if you think visitation would be cost effective or if you can wait for each other. The most satisfying thing in a relationship is to learn that you can wait for each other. The importance of making a plan and working towards it is infinitely powerful and it will certainly strengthen the relationship. Make sure to avoid any unnecessary setbacks, Skyrim can wait if you truly find this woman worth all your time and when it comes to LDRs you really want to be thinking long term, even if you're not talking about it just yet.
As you learn about her, do what you would do with her if she were right there, assess if the things about her make her seem like a worthwhile partner, someone you can spend your life with. You can learn it slowly, or suffer a mutual burst of clarity and love at the very start. I know it may seem embarassing to talk about an LDR (mine started when I talked to my girlfriend on Omegle) but in the end, laugh about it, this is your life and so long as what you chose to do lets you get where you want in life then go for it. This relationship could be the best thing that ever happened to you, or it could leave you lonely and loveless in Jaan, but if you did truly want to go to Japan and followed my advice about falling in love with the country before moving, you're in effing Japan, that place is fantastic! Just make sure you don't sacrifice your ability to sustain yourself for her, because when love becomes dependence, you're just burdening your partner. Learn to love each other and fly together, each with strong wings, you'll learn that love is something that bridges any distance and commitment and strength of spirit will truly let you get anywhere you want to be, cynics may say what they want, but just be better than them and you'll get where you want to be, even in this economy.
I hope this post helps and here's a website for you to look into: http://www.lovingfromadistance.com/
High hopes for your blossoming relationship,
A man who found his love in a far away place