Geisha orgies in wax, vintage porn posters, live horse sex shows (when the horses are feeling up to it), and tableux vivants starring vibrators and whale genitalia are all part of the strange and wonderful world of Japanese hihokan, or erotic musuems, ably documented (with amusing commentary) by photographer Juergen Specht.
Hihokan - Erotic Museums in Japan (photographs by Juergen Specht - via Boing Boing)
See also: Kyoichi Tsuzuki: The Design of Everyday Things (shift.com)