Shuttle House is the real deal but they are in Japan and sometimes takes a while to reply. If they haven't replied in a month, I would e-mail them again. Maybe they missed your e-mail.
Shuttle House is a Yonex authorized dealer. Try contacting them again. They may have difficulty understanding your question since they sort of know English. If you have somoene you know who can contact them in their native language you would probably receive a responce faster.
I' am doing Japanese at the moment for school. Done it for three years and only now starting to make sentences =[
