Incest. Not much explanation necessary. It is something which only in anime can actually be a common trope. Here in the west, I can only recall two shows in recent times that had or featured it. Those shows being the obvious answer Game of Thrones, and American Horror Story: Coven which featured it for a little bit. Besides weird fanfics and shipping, incest is something you don’t really find in western entertainment. Some people I talk to even say stuff like incest is really weird and are usually shocked when it is shown on television. Obviously those people have not watched a lot of anime.
Anime appears to be the only medium where incest is a cliché, people with feelings of incest are pretty much stock characters at this point. Whether it be cousins, siblings, or even worse parents, all forms of incest has probably already been done in some anime.
Incest can be done in comedies, dramas, romance, harems, action; name any genre really. Incest knows no bounds or limit in the world of anime. Off the top of my head as I type this I can already name three anime that have incest;
- Kissxsis (Even though they are step siblings, I’d count it)
- Onii-Sama the anime