This isn't really an "Audience".<br>
While some anime might feature sexual content they still might not be porn. Thats what this "audience" was added for. Only use it when the content is clearly not intended for minors.
For boys. Action, ecchi, or sports, all with a gambatai attitude. People tend to get suckered into thinking that some titles are too explicit to be shounen, in general just because something is full of violence and sexual innuendo it doesn't mean the main audience is young teenage boys. In fact, in probably guarantees it. There are certainly conservative elements in japan, Go Nagai for instance has always been criticised for 'not being suitable', but they don't seem to have the same clamp over the media that the christian right does in america. Shounen series can be vastly popular , and have a habit of running for years.
For girls. Stereotypically romance, but can encompass just as wide a range as shounen.
For young men. Everything from light romance to action gore-fests. The majority of anime produced (that isn't the shounen mega-series) falls into this category.
==How to find the 'target audience'==