Sexy Comic Book Cover Design

Manga titles are primarily classified according to the demographics of their intended audience. The most popular forms of manga target the markets of young boys (shōnen manga) and young girls (shōjo manga). Other categories include adult comics (seinen manga and josei manga) and "businessman" comics. Each of these types occupy their own shelves in most Japanese bookstores. Comics with adult content (ero manga) usually sell in doujinshi stores rather than normal bookstores.
Doujinshi
Doujinshi (同人誌, lit. fan magazine), fan-made Japanese comics operate in a far larger market in Japan than the American "underground comics" market; the largest doujinshi fair, Comic Market, attracts 500,000 visitors twice a year.