Kraken has a team and office in Japan (or at least it had before) but the company is not purely based there. Otherwise, you have BitFlyer which is from Japan and I think Huobi moved from Singapore to Japan, not sure about huobi but bitflyer I am
kraken is leaving japan for good. i guess those regulations got too much to deal with, or they weren't making enough money.
In regards to GDAX institutional accounts; we submitted our application in January, and just received a response a couple days ago >_<
Your own mileage may vary, but I personally would steer clear.
whatever happened to leverage on gdax? it was available to big time customers but then disappeared very quickly.