There will be a second round of anti-nuclear protests coming up on May 7th.

Radiation and the horrors of nuclear catastrophe don’t know any boundaries, this is an international issue. Only two months has passed since the earthquake, and the nuclear accident in Fukushima is still ongoing!
This tumblr site has info (mostly in Japanese) about the upcoming action:
http://57nonukes.tumblr.com/
Here’s some more info from the April 10th action:
http://east306.wordpress.com/2011/04/13/follow-up-teach-in-info-coming-so-stay-tuned/
http://jfissures.wordpress.com/2011/04/15/the-beginning-of-new-street-politics-15000-gather-for-koenji-rally-against-nuclear-power-plants/

They are looking for international solidarity message (with name, job, and then the message in the email body and ‘solidarity message’ in the subject line) to 410nonuke –at– gmail.com, and also info about solidarity actions worldwide.