what has happened twith your situation GrimRoach? I've been living and studying in Japan for a year now and have some advice that might be of help. I don't feel like spilling out the beans so soon since you might have already made your decision, but if you are still looking for advice, tell me.
The only thing I will say for now is this: I dreamt of coming to japan for several years. When I first came I felt so overwhelmed by the many differences between my not so third world country (Mexico) and Japan. I've learned a lot through my interaction with my international community (40+ countries, 100+ people) and the japanese community at my university. Before coming I was so sure I came here to stay and wanted to live and retire in Japan. Now I'm not so sure.
I wont deny it, it is true. Japan as a country is GREAT, no doubt about it. The air is clean, its secure, calm and its easy to live here. But there is one thing that will not make me want to stay here too much. That is japanese culture. I know I said Japan is great, but japanese people, as a society have many traits that i consider less than agreeable. It's hard to define it without going ahead and writing lots of examples, so I will just put it as simple as this: The way the japanese behave and act in their real life is totally different from what you may have experienced as a tourist, their laws and traditions will make no sense to you sometimes, sometimes you might think of them as ridiculous or laughable, but sometimes they will come and bite you in the arse.
If i had the choice, I would never choose to turn japanese 100%. I like that my japanese is good to communicate naturally among them, but there are many traits that are not just what I am at the core, so I will never take them as my own, no matter how japanese I would seem by doing so.
By the way, I dont hate the japanese people, they are cool sometimes and I respect them as human beings. I do like mexicans more though.
Be proud of your country, even if you dont wanna live there.
Finally, no matter what, I would recommend you to come here and study japanese. I'm sure it will be of the greatest experiences you can have. It is possible to make it with just some arubaito, but I would recommend getting some sort of scholarship, there are some REALLY GOOD ONES, like MEXT and some others that will help you live more easily. Just remember this, dont worry if you change your mind when you come, it happens. Give yourself some time, you might love japan again, or you might leave and never come back. Just dont fixate in the idea of staying forever.
To me, coming to japan is a stage of my life, I dont know how much I will stay here, 5 years, 10 maybe. Perhaps even more. I hope that you would consider your case similarly. Coming to japan is a first step, succeeding or failing here will only teach you about life (and failing will always teach you the most, even if it hurts). Once you have actually lived here for a while, you will be in a proper condition to decide if you want to stay.
Dont put all your eggs in one basket and dont burn your bridges. You might want to do something else with your life.
Best of luck!