|Relative(s)|| Genjurou Imari (Grandfather)
Makoto Imari (Older brother)
|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, her mother considered her a demon, due to her lack of empathy and obsession with dissecting animals. When she was six years old, she met her older brother Makoto, who was studying overseas. Eventually, the family couldn't take Ai's strange hobbies anymore and sent her to live with her grandfather, Genjurou Imari.
However, the day before Ai was sent, she discovered Makoto's secret. Ai discovered her brother's porcelain dolls and realized he masturbated to the dolls. She also concluded it was due to an oedipus complex regarding their mother. Ashamed upon his secret being discovered, Makoto threw a teapot full of boiling water on her face, scarring her face forever.
Makoto apologized for the accident, but Maria didn't hold any resentment towards him. Rather than that, she had realized she wanted to mutate and become a monster, in order for her body to change. Some time later, while living with her grandfather, 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. Meanwhile, Maria had decided to use the Pupa monsters to fullfill her dream of becoming a monster. So she and Makoto decided to change their identities, becoming Maria and Hotoki.
30 years later, 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. She then proceeds to go to the island to assimilate Yuu, Utsutsu and Yume with her.
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 and that Maria ate and killed Yuu offscreen. 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.
Thanks to the larvae child inside Maria, Utsutsu and Yume succesfully escape. However, they can't stop the corruption in their bodies anymore, so they proceed to eat each other and dissolve into butterflies in order to escape the corruption. Without the Pupas, Maria returns to normal. But nnow she's a monstruous blob connected to the island. However, she's happy with this outcome, since she got to became a monster like she always wanted. Hotoki finds the unconscious Maria and reveals his feelings towards her, expressing that the Pupa larvae that Utsutsu and Yume left behind can be their child. Maria coldly rejects him, insisting that she only loves her work and experiments. But she also admits it would have been not bad if she has a child with him someday. They finally call each other by their real names.
The "Maria's Island" afterstory shows everything about Hotoki's past with Maria, revealing that they are siblings and he hold incestuous feelings towards her. After the events of the series, Maria continues to live as a monster connected to the island and Hotoki has moved to the island in order to be with her forever.
Because the anime was short, it only covers the first part of the manga, when Maria warns Yume about the butterflies, gives Utsutsu the drugs for Yume and traps the siblings in her laboratory to be experimented on. Her motivations and relationship with Hotoki are never revealed or explained.