I have already reserved a room in a hotel in Ito on the 15th, and was waiting for a cancellation at a hotel in Hatsushima island on the 16th.
Today, I called to the reservation center and found out 30 people in the list still waiting. So I gave up.
I made another one-night reservation in a hotel in Ito, so we will stay in Ito for two nights.
It might be not bad to be relaxed in the same hotel.