Better yet, why don't you switch to the Park Hyatt down the street, pay up their substantially higher rates (say, 40,000 Yen and up), but ask them to give you a room with two of their regular beds. You can then push them together and end up with a bed the size of Lake Superior. You can then comfortably sleep six in it, and the per-person rate is much better than the Century!

We've done that a number of times (join the beds, not have it sleep six) and I had to call Mrs. Pickles on the other end with a megaphone.