Responses
Not even another manga, really, since it's the same author. The main difference is the publishing method. Doujinshi are usually self-published and sold at events, while the rest is published in magazines and the collected into tankouban (that's the pocket book format you also get in English). Some mangakas, especially those who draw yaoi, make doujinshis of their own series to continue the story a bit or to give the characters some extra cute moments.
I arched and I can't find the anime for it even if it has one