It was around 1989 when I was working in Japan a lot and ended up with a Japanese girl friend. My experiences thus far excluded having sex with a woman while she was on her period. One night while we were fooling around I was getting really worked up and wanted have sexual intercourse with her, but she said not during her period. I ended up convincing her to try it and we will stop if need be. Oh my what have I done, she got so hot that she was really sweating and having hot and cold flashes and could not stop taking me on a super ride of my life. I think it was pain and pleasure for her with a little more pleasure than pain. The next night while she was still on her period she wanted to do a little more research in that area.
This woman was very unique for me in that I have never experienced anyone so strong. Imagine someone with a very powerful grip squeezing your hard on very tight where you are in pain saying OW! over and over again. Her vagina was too strong, but dummy me I could not ask her to tone it down a bit.