A character (usually a touhou character), disguised as Hakurei Reimu or wearing a variant of Reimu's costume.
If the picture depicts Reimu with raccoon ears and tail as well as a leaf on head and glasses, this is usually a reference to Futatsuiwa Mamizou's spell card Transformation "Pseudo-Exorcism of the Stupid Shrine Maiden" where Mamizou transforms into Reimu but keeps the animal features and thus, must use this tag if so.
This tag automatically adds hakurei_reimu and cosplay (learn more).