The commercial uses of doujin novels include, but are not limited to: 1. Personal creations: Doujin authors can sell or display their Doujin novels as personal creations without worrying about copyright issues. 2. publish or adapt: Doujin authors can adapt their Doujin novels into comics, animations, games, or other forms of media works and sell or publish them in the market. 3. Creating derivative works: Doujin authors can combine their own Doujin novels with other works to create derivative works such as movies, TV series, games, anime, etc. and sell or publish them in the market. It is important to note that the commercial use of doujinshi novels must comply with relevant laws and regulations to ensure that they do not violate the copyright of the original work. Doujinshi novels that involved copyrights of the original works needed to be handled with caution to avoid any acts of copyright violation.