Hi Lloyd and welcome to CF
I have cruised from the Philippines and HK to Japan
a few times and it is certainly doable but not a practical 2,800nm return voyage for your suggested purpose of a 2 week visit.
windows of opportunity are narrow and because of strong currents, heavy sharp seas are common in even minor disturbances.
The seasonal NE and SW Monsoons don’t lend themselves to a quick turn around and you will find that Japanese Red Tape
for cruising sailors is an all- consuming sophisticated maze designed over centuries to keep us barbarians out.
It is also not cheap!
Having said all of that, I love Japan but would only consider it worthwhile for a minimum 3 month cruise
there over the Cherry blossom season.