a Manga/Anime fic can be written but it should be done with care to prevent weeabo,s from writing a Naruto Yaoi fic nobody want,sPuzzlenaut said:Never ever ever ever ever ever ever ever do fan-fic of an anime or manga if you don't speak goddamned Japanese. In fact, just don't do one at all.
I've seen fanfics easily as bad as My Immortal out there in the form of stupid kiddies who think because they can use a translator they are instantly god's gift to literature.
Also, try to do one based off books rather than films/TV shows, games or comics. It works better.