I don't know who did it, but please don't tag H manga that comes out in monthly publisher magazines like Comic Anthurium as "Doujinshi"; This is just regular H manga and no, doujin =/= porn. If it has a publisher like GOT, Core Magazine or Wani Magazine it is not a doujin.
The Doujinshi tag is for works that are not released by official publishing companies in big magazines, but sold by the authors/circles themselves in conventions like Comiket and online stores like Melonbooks, Toranoana and DLsite. It's for "thin books" as the Japanese like to call them.