BUR #13748 has been approved by @nonamethanks.
create alias pillow_hat -> mob_cap
The pillow hat tag seems to be another one of those concepts that have a specific meaning in the real world, but that on danbooru have been coopted to mean something completely unrelated - in this case "Yakumo Ran's hat"... Except that then our taggers looked at the shape of the hat and started adding it to Chen as well because it was pretty much the same style of hat.
In truth what we're tagging with that tag is a mob cap with (sometimes) animal ear headwear. If you google "pillow hat" you'll realize that our tag has no reflection on reality. And if you google "pillow hat" + "touhou" you'll notice we're the only ones using this term that way.
Before this implication can proceed, pillow_hat -animal_ear_headwear yakumo_ran will have to be sorted out.
Updated