A hentai manga site is a porn comic/cartoon website typically of Japanese origin. Hentai manga often is liked for its exaggerated cartoons which emphasize fetishes such as large breasts or muscles. Hentai manga is also commonly used for fetishes in general that might otherwise be difficult to do in real life or not possible at all because the manga may only exist in fantasy such as the use of tentacles or video games.
The most common type of hentai manga is the recreation of video game characters and celebrities put into porn scenes. Video game characters in particular are often used without legal issues arising from the manga. According to Reddit, one of the most common video game characters used in hentai manga is Chun Li from Street Fighter.
Some of the most popular hentai manga sites include nHentai, Fakku, Gelbooru, CartoonPorno, and Manytoon.