The rules do seem inconsistent.

At Sheraton Sunmarina Okinawa they prepped the room with four beds and at checkin said the extra charge would be ¥12,000x2 per night. I told them we didn’t need extra beds and would make due with the twins and sofa bed. They let us keep the beds the first night, and removed the sheets for nights 2 and 3. We they got an upgrade to a much nicer room for the last two nights and they fitted the sofa and Murphy bed with sheets, no extra charge. Go figure.

The first time I stayed in Hakuba they said there would be a charge for 3rd and 4th person, but a chat with Marriott cleared that charge and we haven’t had a similar situation since. That room had twins plus futons.