You'll never have experience needed to be fluent in the language without being thrown into it. You have to talk to people. You may be able to learn how to
write in Japanese, but verbally communicating is a completely different level.
My Italian is utter crap. I can write and translate it fine if I see it in text, but I can't get a clue listening to someone speak Italian. Even if it's really basic, I'm just not used to it. This is after three years of studying Italian, and let's just assume I was out 60 days out of the 405 (approx.) I was in Italian. (Why am I out so much? I'm a bit of a weakling, plus you can thank chronological depression for something, I'm sure.)
Yeah, it's hard learning a new language. The thing is that Italian's
easy for a native English speaker to learn, since it's a Romance language, and sentence structure is similar. (Completely random, I heart double-negatives. They're SO fun!

) For an English speaker, Japanese is going to be hard to learn since it's so different. You don't even use Roman Text, you use Kana and Kanji.

It's like starting over from kindergarten.
But it you really want to, whatever.

Throughout my lifetime as a fangirl (and the seventh top posting regular in the history of Animelyrics.com *beams*), I have encountered many a fan who says they want to know Japanese. Few make it to the level where they can actually transliterate lyrics, translate manga or subtitle anime. Some sadly don't get passed greetings, suffixes, swearing and dirty language. But most fans know enough Japanese (or at least, have a wide enough VOCABULARY SHEET) to play a decent game of Shiritori. (I also heart Shiritori.)
So what have we learned? Japanese isn't a Romance language, I need to stay in school more, and Shiritori is a striving Nihongo-learner's friend.
