Is there a convergent plate boundary off the east coast of Japan?
In part, yes, there is. The Pacific plate and North American (yes, the North American) plate converge off the east coast of Japan’s northern islands. Further south, the Phillipine plate and Eurasian plate get into the act. Use the link below to check out a post and a pretty good map of the action. The link is to Wikipedia, and they’ve got the goods.