“Seinen” (青年), on the other hand, refers to young men between the ages of 15-24. Seinen anime and manga tend to be of a more violent and/or psychological nature than shonen series—though, of course, there are seinen comedies as well. They can also have content of a pornographic nature (though this is not the focus of the work). Famous seinen anime and manga include such titles such as Berserk, Ghost in the Shell, Akira, Hellsing, and Gantz.
via How to Identify the Basic Types of Anime and Manga.
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