Cheapest accommodation in Motobu, Okinawa?

I'm interested in finding the absolute cheapest place to sleep overnight in Motobu, Okinawa.

There doesn't seem to be any hostels on the usual websites but I've noticed that there seems to be a kind of "flophouse" in Okinawa that I've never encountered in other parts of Japan. In fact I'm staying at one now in Naha for 1,000 yen per night (roughly $10). I think some of these call themselves "share houses" in English. But outside Naha they might not use English? Most of the guests are middle aged Japanese staying long term. Others including backpackers stay a night or a week.

I don't know what these places are called in Japanese, how common they are, or how people normally find them.

For the purposes of this question I'm not too worried about luxury or quality. The place I'm in now is messy and even in some respects a bit dirty, but the people and atmosphere are great.

I'm interested in any type of cheap accommodation including campgrounds.

(I know I could sleep outside or try CouchSurfing or a similar website, but I don't consider those to be what this question is about.)

The reasons are there's a ferry that leaves from Motobu and that I'd enjoy staying a night or several in a part of Okinawa where there are no tourists.