Mosquito Amanto is an amanto that was staying secretly in the Shinsengumi headquarters. She is the main antagonist of Episode 20.
Not much is known about her, except that she was involved in an affair with her boss which got her pregnant, and resulted in her having to take blood from humans for her baby.
She has long black hair and black eyes, and has chalky gray skin. She is shown to have wings that enable her to fly which also makes a buzzing noise, just like a mosquito. her tongue is shown to extend greatly, which is what she uses to drink blood from her victims. She wears a red kimono.
She was initially mistaken for the woman in the red kimono from all the horror stories that were being told, and due to her ghastly appearance, she was mistaken to be that ghost. Everyone in the headquarters were deceived into thinking it was actually a ghost because of the story, but it is revealed that she is only an amanto bearing mosquito like qualities, such as being repelled by the mosquito coil and drinking blood from her victims with her tongue. It is shown later when she is tied up by the Shinsengumi the reason why she attacked their headquarters was because she was pregnant and needed more blood than usual from "hot blooded men."