I have heard and read that Japan is "sexually repressed." For the most part, I would say there is not very much sex appeal used in advertising here. And while people do seem extremely conscious of how they dress and present themselves, celebrities and regular people alike tend to dress less provocatively than in the U.S. Now, making no comment on the pros or cons of a culture being "sexually repressed," I will say that sex seems to come out here in ways that I have been unaccustomed to.
For example, I often see people reading magna, a kind of Japanese comics, on the train or in convenience stores (it is perfectly acceptable to read magazines in stores with no intention of purchasing them). Magna takes on many different forms, but one kind, called seinen, is geared for young adult males and often contains pornographic material. Usually, I avoid looking at people or what they are reading while on trains -- because people usually keep to themselves here, and so I would feel intrusive -- but one of my coworkers says she has often seen people reading this seinen magna on the train.
Seinen can also be found in anime, a type of Japanese cartoon. For example, I was watching TV the other night, just before midnight, and I saw a series of anime girls become undressed. They started out wearing (mostly schoolgirl) clothing, but as a car drove over the curves of their bodies, the clothes would disappear to reveal nothing but barely-there lingerie. The series went on for long enough, that I had time to be semi-shocked (I don't even have cable), and still to grab my camera and actually record a few of the scenes. If you want to watch, the video clip is below:
This video clip brings up another point. There seems to be a (sexual) fascination with school-aged girls. Many schools require uniforms, and I have been surprised by how short some of the pleated skirts are. It seems to be okay for older men to have an interest in them as well.
And this brings up the point that I have had a few interactions with older (including married) men flirting with me, which I find quite uncomfortable. This isn't at all the norm, by any means, but it has surprised me how the age differential (and the married factor for that matter) didn't seem to be an issue for them. Now, no need for anyone to be worried, I have been able to deflect and defend myself fine from these come ons. I just find the seeming acceptableness of this off-putting.