Originally Posted by
LCUF
I think my response was targeted at the love hotel room and not regular hotel room but I have no proof that love hotels wouldn't accept three people in a room either, although the love hotel rooms are very unlikely to have more than a single king bed, at least I don't think I have ever seen a love hotel room with twin beds or maybe I wasn't thorough enough in checking every love hotel room possible! :P
Oh dear. The misunderstanding came from the idea that the OP wanted a room for three people. He said he didn’t.
Some Love Hotels DO allow more than two people in a room. Not all do, and the majority will not allow three people to stay. But this generalisation covers the whole of Japan. It may not be true for Shinjuku (or Shibuya)
Shinjuku happens to be the place where the love hotels I know of that do allow more guests are located. Some require an additional fee of 50%, some don’t, some have party rooms whole groups can hang out in. It depends on the hotel’s own policies.