At the Nihongo learning it is imperative that we look for multiple sources of content that can help accelerate our language studies.
For those who decided to learn Japanese on their own and use the internet to find materials to study the language, as well as the Professor Pier said that to learn even if you are self-taught, let's then list 5 sites that help to learn/improve the Japanese language.
5 sites to learn Japanese
Erin's Challenge
Erin is a website very cool that gives classes through videos that have options to put subtitles in japanese, portuguese and romaji too.
busuu
Similar to sites like Duolingo, in Busuu you learn through interactive presentations. After watching them you can review them and check if they are correct by answering the questions regarding the lesson you just studied and you can even download the lesson PDF.
NHK World
Yes, it's that pay TV channel, which has a radio and a website as well, it offers a course in 50 lessons so that anyone can learn Japanese. Lessons are in mp3 audio and PDF handout for download, more details click here!
italki
Focused more on conversation, you have the possibility of taking classes with native teachers to practice your speech and improve it, visit Italki by clicking here.
tune in
Tunein is more than an online radio site, there are thousands of online radio stations from all over the world. Excellent for searching by countries, which in this case is Japan, and listening to news radios, music and much more! Great for inputting, in addition to listening through your favorite browser, it has apps for Smartphones, Tablets and TVs, more details by clicking here.
I've put together some sites that could leverage your japanese and improve your vocabulary. Good luck and don't forget to do a lot of input.
Ganbatte!