We had an amazing stay here! The rooms were very clean and spacious. The complimentary breakfast was amazing. They had both Japanese and more western breakfast options, with an omurice station, fresh croissants made every half hour or so, curry, fish, fresh fruit just to name a few options.
The staff was incredibly kind and friendly, making our stay extra special.
As for the private beach, you can pay about 4400 for use of the indoor/outdoor pool, kayaking, paddle boats, a beach chair (coats less for children). This is a one time charge for use throughout your stay. You can still access the beach without this pass- you just will not be entitled to a beach chair. Both pools were quite nice.
They also have an onsen that is quite nice after a long day!
We really enjoyed our stay and will definitely return!