Hong Meiling is a youkai, though it isn't known to which specific category she actually belongs. She guards the entrance to the Scarlet Devil Mansion along with her henchmen. She is known for her mastery of the martial arts, part of which can be seen from her movement which is performed with Shin-Kyaku (a move in Chinese martial arts).
During the events of Embodiment of Scarlet Devil, she bravely fought against the intruding heroines but ultimately failed to complete her job.
(Source: Touhou Wiki)