this site is the perfect immersion course. What it does is it puts you in a Japanese elementary school environment (literally). It features little animations that you would experience in a Japanese elementary school. It is all natural with no translation. There is another part of the site that brings you to a hiragana and katakana chart with no romaji. You just click on a hiragana/katakana symbol it will say the pronounciation along with an image that tells you what to do with your mouth. Then at the bottom of that page there are pictures of different things with the name of it written down in kana (exactly like the abc charts from elementary school). Click on it, and it will say it. Lets just say that this website teaches you Japanese very, very, very naturally.
Here is the link to the site: http://www.hellonavi.com/foldera/html/japanese.html
Bookmark it.