We stayed for two days. The place really picked up after 2 pm on Sunday but still relaxing.
Probably an exception, the Japanese as a culture are comfortable with nudity :-) ... and they love their hot springs, crazy TV shows and many other interesting things. My wife at the time was doing a lot of business in Tokyo a few years back and so I joined her for a month there. Her coworker invited us to hot springs and it's all nude. They have a few mixed gender ones away from the city, but knowing someone local is the way to go otherwise we would have never known. They didn't care if you were nudist or not ... you will get naked! ... and they have excellent adherence to taking a shower before soaking. Three things they were eager to share with us: their temples (we drove 2 hours to see one), the hot springs and great cheap local food - I ended up picking up the tab for 5 people, with alcohol and a four course meal all for $120US ... whereas a coffee and cake will set you back $40US in the touristy Ginza district - this was in 2008.