A group of us popped into Bell Hills one night to use their onsen because our pension nearby did not have one. We were charged 1080yen for access and a separate 200yen for towel. This was by far the most expensive onsen I have come across in Japan. Worse, the onsen was tiny and did not provide the usual amenities (comb, toothbrush set, cotton buds, hair styling aids, stools) and was really below average. The added insult was that we found out afterwards that they charge locals only 500yen, so foreigners pay more than 50% surcharge.