[odonata]

My first sento was comical. So I paid at the desk and went into the changing area, got my locker and proceded to get naked. There were about 6 other men there and I got some looks for being gaijin. In the changing area there were a few tables and chairs and two massage chairs. Three of the naked patrons were sitting at a table and chatting while observing the strange gaijin.
So I entered the washing area and was about to get clean when I realised that i had bought nothing with me. No soap, shampoo or towels. I left the wash area and started to ask my fellow naked humans in broken japanese what the deal was with the soap and towels.
After some laughing and joking I was directed to talk to the woman at the reception desk through a curtain and for a small fee she gave me some soap, shampoo and towels. She could clearly see me as we done the deal but I guess she sees that kind of stuff everyday.

So off I went to try again. The freedom of having a good soap down in an area built for it is great and pouring buckets of hot water over yourself is a nice treat.
Then I hit the sento proper. Anyone who says "putting your head under the water is bad ettiquet" is mental. The reason you do not put your head under the water is that your eyes will cook then explode as the water is soooo hot.
I could only bare about 2 minuets before I jumped out looking very red to the amusment of my fellow naked bathers.
One guy suggested that I try the far sento as the water was cooler and he was right. I did manage a ten minute soak in that one.

Back in the changing area getting dry I ended up teaching a few english words to a couple of naked japanese and getting a good lead on a local onsen.

Growing up in the UK I went to an all boys school and we all had to shower together, I really don't see any difference using a japanese sento/onsen.

For the people who feel embarassed or shocked I would suggest that you have some issues about your body image that are not held by other people that you would bath with. It is only your own issues that stop you from enjoying a great water based experience.
Lets face it, if you are a tourist in Japan it is very unlikely that the people at the onsen will ever see you again after you leave. it is not like they are going to phone your friends and family and tell them what a big rear you have.