Seinen, like shounen, is a genre of anime that’s intended for the boys, but not little boys, we’re talking 18-45 year olds, kind of a big range. Anyway, there’s a big emphasis on mature content like guts and gore, lots of juicy harsh language and swearing, partial and a lil full-on nudity (but not the main focus), and just altogether more complex plots that require you to think a little, but there’s still a wide range of topics covered like science, fantasy, sports, et cetera.
I’ve honestly never heard the term seinen until my buddy told me about it, yet I’ve been watching them this whole time. Wiki has the definition as: cater specifically to men’s interests, and are marketed towards a demographic of older teenage boys and adult men between the ages of 18 and 45…Seinen manga can focus on action, politics, science fiction, fantasy, relationships, sports, or comedy. The female equivalent to seinen manga is josei manga…A common way to tell if a manga is seinen is by looking at whether furigana is used over the original kanji text: if there are furigana on all kanji, the title is generally aimed at a younger audience.