We did some research on the web and summary as the following to help those who are interested in learning Japanese free.
Online free resources
NHK Learn Japanese Online with Video and Audio
This website has 10 online lessons.
This website has 10 basic Japanese lessons and 13 intermediate Japanese lessons.
This website provides English Japanese dictionary.
This website provides online lessons, flash card trainers and language reference.
Learn Japanese a Kanji a day has four study levels, and Japanese-English dictionary.
This website provides online video and audio Japanese lessons.
Free download at the Japan store including kanji and listening practice.
This website has Japanese online lessons and articles on Japanese culture.
Japanese Learning Tools on Web
Some free podcasts
Using Podcast to learn Japanese is very convenient, because you can take the podcasts with you anywhere you go.
Help Kids to Learn Japanese