This is a university in Washington state which I recently graduated from. They have a special education master's program:
http://www.acadweb.wwu.edu/gradschool/programs/program_details.asp?Program=1041
It is also said for certified teachers, but I know a Japanese person in this program. There might be some exceptions, so I'd recommend directly contacting university/department that you are interested. Gannbattute kudasai ne!