Japan is pretty abysmal for Marriott as others have pointed out. You will also want to keep in mind the weather at that time of year. If you are from the south or the east coast it probably won't bother you, but it is extremely humid so make sure you bring some towels with you as you will be sweating a lot.

You might want to pay out of pocket for a more traditional style Japanese room in somewhere like Kyoto. You might also want to budget for rail passes.