A huge majority of anime feature younger characters so I decided to look for some that have adult ones. These characters are 18 or older and are experiencing the wonders of adulthood. Let me know if I should add any more.
List of anime that adapt manga from Shogakukan's "Shounen Sunday Comics" imprint and its various sub-imprints. [First Seasons Only]. The imprint contains manga from the following magazines: Weekly Shounen Sunday, Gessan