Phantom Daughter, alias Yuuri Kumoi, is the daughter of the head of BLACK PHANTOM. She dresses in a gothic lolita fashion has long hair, and is of the same age as "The Children". She is an esper, her power being to put people in a different mindset, for example, Minamoto becoming a child in mind only, while Hyoubu from P.A.N.D.R.A. placed an illusion on him, making him seem like a child in every other way. She seems extremely loyal to her father, although when she meets Kaoru and reads her mind, she finds out that she is the Queen of Catastrophe, and seems extremely glad to have met her. She might think of her as a savior of some sort. At the end of the anime, Yuuri seems to have been liberated from BLACK PHANTOM, and is in fact joining the same middle school as Kaoru, Aoi and Shiho. Although it is known that she is the daughter of Black Phantom, not much is known about her, although later, Yuuri is revealed to have multiple personalities. So far, her known personalities are:
"Yuuri Kumoi", a normal shy schoolgirl with dark hair who is actually a fake personality (but is unaware of it), created by "Mirage" to live her day life for her.
"Mirage", the true personality (who appears with blonde hair). She appears to be starting to rebel against her father. Mirage created Phantom as an outlet for her feelings due to not being able to express them in any way. While storic and devoid of feelings most of the time, she is very protective of Nai.
"Phantom", a more sadistic personality who houses the supposed true intentions and feelings of Phantom Daughter, who wants to 'play' with "The Children" forever.
"Feather", who is able to store her 'self' outside of Yuuri's body into a set of special earrings (these earrings resembles the one worn by future Kaoru in the visions). Originally thought of as another personality, Feather believes she may actually be someone else completely, as her memories are different from the other personalities of Yuuri. Feather wishes to protect Yuuri, along with everyone else. She gives one of the special earrings meant for Kaoru to Minamoto, asking him to investigate it. Feather seems to be attracted to Minamoto due to his beliefs and to a possible past with him, and kisses him, which Kaoru accidentally witnesses. After some research from Fujiko in the Impalahen kingdom, the origin of the earring, Feather apparently surpasses the strength of level 7 espers. Even though Feather doesn't have teleportation her extreme degree of strength with psycokinesis allows her to move at speeds which surpass teleportation. Later events caused her to leave Yuuri into the care of B.A.B.E.L., where she eventually possessed a special gel-like material with special quantities, and formed into a human woman's body, although due to the strain from saving Minamoto and exercising various different level 7 powers, including healing severe injuries and teleportation which she lacked before, she reformed into the shape of a bird. She is now in the care of Minamoto, as B.A.B.E.L. is unable to contain her.
The Children still do not know who she really is outside of school life. Shiho has been shown to be suspicious of Yuuri, being more empathic in nature. When she is the daughter of Black Phantom, her name is spelled in katakana, while when she is a regular student, it is spelled in kanji. Yuuri's powers seems to vary greatly; she can use illusions to fake her location as well as make decoys of herself, teleportation, psychokinesis, flight, and grant herself abilities (such as playing drums) to her "Yuuri Kumoi" personality when required.
Mirage" (ミラージュ), the true personality (who appears with blonde hair). Her real name is Yuuri (ユーリ), but is identified as Mirage for the sake of preventing confusion. She appears to be starting to rebel against her father. Mirage created Phantom as an outlet for her feelings due to not being able to express them in any way herself. While storic and devoid of feelings most of the time, she is very protective of Nai, her bodyguard.