The almost laughably euphemistic Japanese name of this museum can be translated as ‘Museum of Secret Treasures’, while the English description – Atami Adult Museum – is more matter-of-fact. Housing a collection of sex- and sexuality-related paraphernalia from all over the world, the museum is one of many that were built in resort towns all over the country to attract dating couples and newlyweds. While most of them disappeared as soon as the next entertainment trend came along, Atami's Hihoukan still stands strong. Although it's more retro than risqué by today’s standards, you still need to be 18 or older to get in.