|Relative(s)||Genjurou Imari (Grandfather)|
|Debut||Chapter 1; Episode 1|
Ai Imari (伊万里 愛 Imari Ai) also known as Maria, is a mysterious researcher who seemed to have knowledge about the Pupa virus and is currently doing experiments regarding it.
Maria always wears a long black dress and a black hat. She has long black hair and bangs that go to the left. She has a scar on the right side of her body.
She does not seem to care much for almost anyone or anything, treating everything like guinea pigs and test subjects even from an early age, as seen when she dissected the Pupa monsters when she was young, and also didn't mind using Utsutsu and Yume as guinea pigs to observe the Pupa virus.
Like her grandfather she has a lack of empathy for living beings and is willing to exchange the lives of many innocent people to gain information about the effects of the virus.
As a child, she was scarred during an accident. She was already stoic and had a lack of empathy since then. On one of the visits to her grandfather's house, she found a pair of monsters in larvae form in the forest, the Pupa monsters. This picked her interest and for years she dissected them in order to know about them, with the help of her grandfather's associate, Chiharu Bizen.
However, after 30 years, the male monster escaped from the laboratory and the female monster impregnated Sachiko Hasegawa and reincarnated as a human. Ai continued researching with what was left of them. It seems that she and Bizen had their differences when it came to their methods of researching, so Ai went on researching on her own with her followers.
She appears to Yume while she is in the way to school, warning her of the "red butterflies". After Yume became a monster, she gave Utsutsu a drug that temporarily suppresses his sister's rampage in exchange for them being examined. However, Utsutsu is tortured and dissected without anesthesia by Maria's crew, causing Yume to transform into a monster and make a rampage to save her brother. However, utsutsu manages to escape from the doctors on his own and they're rescued by Yuu.
Despite Utsutsu and Yume escape from the hospital, Maria manages to get some of the Pupa D.N.A and impregnates herself with it, so she could understand better about it. She spends in her laboratory for several days as her assistant Hotoki takes care of her. When it seems that she is about to "give birth", she goes to look for Yume, the tests indicating that she is a monster.
Maria succesfully finds Yume in the forest, having returned to her human form after another rampage and Utsutsu unconscious. She turns into a flesh blob and proceeds to absorb Yume. When Utsutsu wakes up, he realizes that Yume is gone. Demanding to know what happened, Shiro attempts to tell him that Yume is not the innocent girl he believes her to be and that she is a monster. Utsutsu insists that Yume is Yume and goes to save her, getting absorbed by Maria too.
Inside Maria, Utsutsu searches for Yume, only to arrive when a flesh tentacle cuts her head. This only suceeds in Yume recovering her memories and returning to her larva form. Then, the assimilated form mutates into several Yume clones. Utsutsu falls into despair, finally acceppting what Yume is and becomes a monster who starts devouring the Yume clones.
After Utsutsu returns to his senses and Yume returns to her human form, both proceed to devour each other as they happily embrace for one last time and both melt into a cloud of red butterflies. Maria survives and is freed from the monster, but not before giving birth to a Pupa larvae.
Because the anime was short, it only covers the first part of the manga, when Maria warns Yume about the butterflies and gives Utsutsu the drugs for Yume.