Decided to combine this with our Chureito Pagoda visit. The bus ride from Mount Fuji station was fairly straightforward. There are separate areas for male and female - blue for male, red for female, if I recall but do check. The men's outdoor onsen is about 100m from the indoor onsens and down a flight of steps - its a bit chilly without clothes on(!). The onsen users consisted of local Japanese men, not touristy at all. The outdoor onsens pools are very relaxing but you can't see Fuji from them. The timetable for the return bus trip was a little confusing, as was the payment for the fare - you pay on exit(!)

Modern well organised large Onsen with many different baths both inside and outside. Gender separate, no bathing costumes allowed as per the Japanese way. Beautiful views of Mount Fuji whilst bathing outside, amazing! Not too expensive either.