Crappy fact about Japanese hotels
In Japan hotels charge you per person, not room. A few times we made a reservation for 2 people over a hotel booking website and arrived to the place where the receptionist told us they didn't get the memo and we should pay double for the stay. In the end we never paid double, but even having to have this conversation is unnecessary...
If you stay in a hotel in Japan, be careful and maybe confirm your reservation details over the phone prior to arrival.
Also keep in mind that this is a generally punctual nation. If you leave your room only a few minutes after the checkout time, they might charge you another night.
We're in a hotel room in Kimitsu at the moment, where we missed breakfast by a minute and just in case called to extend our checkout for an hour for 500 JPY. We don't like being rushed out. Other guests were obedient and left already - it's 10:20 and the situation in the hotel is apocalyptic:
Off now, time to ride the streets of Chiba!