What is Doujinshi?

Doujinshi are self-published works, typically manga, created by fans or independent artists. In the context of adult content, doujinshi refers to fan-made hentai manga featuring characters from popular anime, manga, or video games. Comiket, held twice yearly in Tokyo, is the world's largest doujinshi event. Sites like nhentai catalog hundreds of thousands of hentai doujinshi. The 6-digit nhentai number system has become internet culture.