I think this is a horrible idea. I can all-but-guarantee you it will become the most-overused and abused tags on the site.
Questions tagged anime
This tag indicates that the question is specific to the anime version of a series that exists as both anime and manga, or movie(s).
I get that some questions are about an anime-specific version of the work — so describe that in your question; not with tags. Otherwise, we'd have a movie tag on our Movie & TV site used only for movies that just happen to have TV versions. Sound silly, doesn't it?
Users are never going to understand that an anime tag is only for questions that are specific to the anime-version of a series that exists as both anime and manga. Users are going to try and use this for every question that is either anime or menga.
But your can't divide a site into large swaths like this. These discussions go back as far back as our Cooking site when some folks were only interested in "savory vs. sweet" while another wanted "vegetarian vs. non-vegetarian." The tags will convey no useful information. At best it will be a horribly incomplete categorization system.