A common American or Western assumption is that sex and sexuality expressed in any media form, such as anime, is there simply to satisfy the male fantasy. To some extent, the inclusion of sex in anime can be to appease male viewers and is for solely entertainment purposes. There is definitely an element of it, especially in anime targeted at the male audience, where women are presented in highly sexual forms with large breasts, are scantily-clad and seductive. Such female characters may appeal to the male ego. Also as it is privately consumed, anime is a socially acceptable way in which male fantasy can be satisfied.
However, such an assumption is a simplification and perhaps a result of the fact that Western animation tends to be confined to children’s cartoons, without exploring any adult issues.
Sexuality and sex anime does not only appear in anime targeted at men only- for instance, the prevalence of homosexuality in shojo anime. There are instances of sexuality in some shape or form in nearly every anime.
Additionally, such an attitude assumes that sexuality in anime does not appeal to females. There is evidence to suggest that women also can derive pleasure from portrayals of sexuality in anime. For example, high school girls- the object of male fantasy- also appeal to women as that age in life tends to be idealized in Japanese society.
Often sex in anime has greater depth and symbolic meaning than merely physical sexuality or naked women. Apart from hentai obviously, there are many instances of implicit sexuality and sexual innuendo which suggest the anime appeals to more than just male carnal urges. The creator may be making some kind of social commentary, criticizing some aspect of sexuality in Japanese society and expressing a desire for change, or else reflecting the dominant attitudes towards sexuality in Japan in general.
What is also surprising is that in many instances such sexually charged anime are created by females, and also in many instances directed at females.
Additionally, some anime seem to mock male attitudes to attractive women etc, by presenting them in a comedic light or depicting men as weak under the influence of a seductive woman.