We would recommend to book the green or blue room, which both are very spacious, airy and have nice seaviews .
It's a quiet place, the restaurant closes at 9pm, there's almost no traffic.
Many birds and occasionally geckos add to tranquil atmosphere.
We were staying in the terrace room, which was "basic" but had everything we needed, including air-conditioning, fan, kettle, TV. We would have had a private terrace in front of our room, but it was not too inviting - it's by far nicer to sit on the restaurant's terrace :)
The airbeds were just ok to sleep on, as long as we didn't move, since each little movement on these matresses causes loud sqeaking noises, each time one of us turned, we woke up :/ For the price we would have expected better.
No WiFi in the terrace room, only in "blue room" and "green room". The WiFi in the restaurant wasn't stable and we couldn't use it after 9pm.
The family is very sympathic and helpful, but without speaking Japanese you might find yourself a bit "lost in translation".
If green or blue room would be available we would stay there again :)