I'm not an expert on Japanese onsens, and regret not having tried more during my several years in Japan. For me, i just never got into the communal water thing. But, putting that aside, I tried Only You with my wife and daughter, following an afternoon at in the woods in Hakone, and it was just lovely. We rented a room for a couple of hours and it was a nice treat. We had a lunch buffet which was generally to a decent to high standard of mixed, light Japanese food. After that, the room is about the size of a regular hotel room and has a nice big wooden tub which my daughter enjoyed. Meanwhille, i just went right to the resting room and took a nap. So, to be fair, i didn't even step into the onsen, but i did walk around a bit after my nap and it was a very peaceful experience as the place is located in the forest and it's nice to lally gag around, drink some tea and just relax. the japanese locals sure knew what they were doing, and enjoyed it, so i can imagine this is to a decent standard. I don't think this is a destination for an onsen, but if you're doing a trip to this part of Japan, it's a good treat in the agenda.

the spa is in the middle of mountain where is close to DAIYUSAN-SAIJO-JI temple.Shuttle bus is pick up at the daiyusan station,izu-hakone line or kaisei station,odakyu line. the spa is really surround by green,sure it's in the middle of mountain!it's one day spa,and you can stay at the hotel of the spa.I recommend you there if you want to relax ,want to do anything and escape for a day.you can go there for one and half hours by odakyu line or by your car.there's no onsen area like hakone even only you is close to hakone.anyway just do relax!!