Sira wasn't being at all mean.
You'll have to have a marketable skill that is desired in the Japanese workforce to the point that someone would hire a foreigner to do it, because there are loads of talented people already in Japan that don't require visas. Unless you have a great talent you aren't necessarily going to be their first pick.
Second, if you go on a student visa, you can't just live anywhere. You'll have to be close to your school, and there are strict rules you have to follow about how much you're allowed to work. Also you will have to be IN school the entire time. The Japanese government doesn't play around with people who don't have the proper reason to be in the country.
The reality is this: Japan is another country, another culture. They speak a totally different language. You want to talk about culture shock? Run over there and throw yourself into a small Japanese town. I hope it will be everything you dreamed, but I doubt it.
Since you're young, and you have plenty of time, try studying the language for a bit. Learn about more than Japan's entertainment exports, and do some actual research about the places you might think you will be most comfortable. If this is a serious dream then it will require serious work.