The sources I found

I searched about the racism, discrimination in Japan, especially focusing on the burakumin.
Those are the sources I found.

Video:http://www.youtube.com/watch?v=Chv6nzNfq54 (Title:the marriage discrimination and the buraku problem.)
This is a news program about the discrimination against Burakumin. They reported that there was the discrimination about marriage of a person whose relatives were from the buraku.
I learned that even in present Japan, there exists a discrimination against the people called Burakumin and the range of discrimination is extended to the marriage.

Forum:http://www.jref.com/forum/archive/index.php/t-335.html (Title:Burakumin[Archive]-Japan Forum )
In this forum, people discussed the problem of discrimination in Japan, such as buraku or ainu.
Some people wrote that the origin of the discrimination against burakumin is the idea of Shinto and to me, it's a new information and worth researching.

Web site:http://blhrri.org/blhrri_e/blhrri/buraku.html (Title: What is buraku discrimination?)
This is the site of the institution that tries to protect the rights of discriminated people in Japan.
In this page, there are much information about the buraku liberation movement and I can find the recent situation of buraku discrimination.