Seinen

Anime and Manga targeted at male audiences aged 18 to 40. It is the older counterpart of Shounen and male counterpart of Josei.

Before adding a new title, please double check your sources. A Seinen manga has to be published in a Seinen magazine for it truly be part of the demographic. For an anime, go check its usually late night time slot in Japan, or any slot if it airs in a satelite channel (again in Japan). Also check if it obviously has glaring mature imagery; especially if the anime is based from a Shonen work, the animation must be way more mature than its source material.