About booking a Japanese hotel for two people.

Don't do this. The Japanese are very serious. There must be a way to find out how many people you live in, and you will make up for it. Besides, it's not appropriate to do so. . .

By the way, actually, I did it once. Once, my husband and I went to Hakone-CHO. We originally wanted to go back and forth the same day. But then I wanted to stay one more day. Sadly, it was the three-day break of the autumn leaf season, which was also the tourist season. All hotels don't have double rooms. Later, I looked around and finally found a single room in a hotel. However, the Japanese are very serious. He won't allow us to stay, and we can't afford a double room. Finally, my husband booked this room by himself. Later, I sneaked in, but before long, I was knocked at the door by a serious waiter. Finally, we negotiated to double the money and let us live. But he didn't agree to the plan before. Oh, you're welcome

So, whatever your reason, don't try.