Language school in Japan?

I was wondering what you guys think of Language school. I want to go to Japan for 6-12 weeks to follow a language course. I hope that by being around Japanese people and the language learning will go even more quickly. I already know quite a few words but the grammar and kanji is also important. I started in October with RJ but the last few weeks I'm really getting obsessed with the language and I'm also using other aids (books + Youtube etc,...) to even further my knowledge. I currently however am not studying Japanese with a university, but just for myself trough RJ and a lot of books. I don't know how strict these schools and the Japanese government are, but it seems some of the school have some requirements, like a Japanese study in country of origin. I'm I understanding it correctly or can I just sign in for a course? If it's possible to go, does anyone have any tips or recommendations which school to check out and where to stay for the duration (outside of what those programs offer).

If anyone has information on this I'd appreciate to know as well. Considering I'm going to be living in Japan next year, it'd be nice to have a Japanese class after high school at night. It'd almost be like I was going to cram-school except I wouldn't be because it'd be about Japanese grammar, kanji and etc. rather than college entrance exam studying. Thank you to anyone who helps us out! Derek 皇子山出礼句