I read this one a long time ago. It's about a man who is riding a train, but arrives at a town that he has never heard of before. In this town it's normal to have casual sex with anyone open on the street. The man tries to follow a girl that reminds him of somebody, but he is always hindered by people wanting to have sex with him. I also remember that he develops a strong libido that allows him to keep an erection indefinetly, but because time in this town is flowing faster than normal it's draining his life force or something. It was a weird but interesting read, I hope somebody knows the title.

Edit: I found it myself. It's called Uroshima Monogatari.