Is this your first trip to Japan? Hotels rooms in Japan make many of those in Europe look roomy. The single rooms at the best hotels are veritable closets. The smallest room at the PHT is larger than 98% of hotel rooms in Japan, from my experience (10+trips to Japan). A diamond upgrade is a very rare thing at Japan Hyatts in several dozen stays (in all of the Japan Hyatts), other than RC upgrades, I think I have only gotten two true upgrades one to a corner room at the PHT and, this year, to a "grand" room at the GH Fukuoka.