Many doujinshi covers feature gratuitous fanservice to attract buyers.
Doujinshi (also spelled dōjinshi) are self-published Japanese works, such as manga, novels, and artwork.
Doujinshi are often based on characters and settings from existing professional/commercial works. In the case of artwork, these are called fan art, in the case of stories, fan fiction.
Doujinshi is also a Japanese manga magazine published by fans, as such tend to be noncommercial.
Spanking in doujinshi
Examples of spanking in hentai doujinshi can be found, for example, on the site nhentai via the search spanking doujinshi Warning: .