No issue that I know of, there are lots of users of Japanese market DD TT here myself included.
As long as the step down is doing its job and just about every one out there is more than capable of handling the very small load from a DD TT you should be all set with a Japanese market unit.
As long as the step down is doing its job and just about every one out there is more than capable of handling the very small load from a DD TT you should be all set with a Japanese market unit.