Currently, JDK cannot be downloaded through Japanese page. It timeouts when clicked Download on following page.
http://java.sun.com/javase/ja/6/download.html

I'm not sure if this is intentional but it seems that English page is pointing to cds.sun.com/.... and Japanese page is pointing to cds-edit.sun.com. The same applies to JRE. However, no problem for JRE at this moment.

Another thing I noticed is that English page and Japanese page has their contents in different order. English page has JRE, JDK, JDK with Java EE, JDK with NetBeans, ... but Japanese page has JDK, JDK u7 Itanium, JDK 7 with Java EE, JDK u10 with NetBeans, JRE, ...