Lucy
Lucy (ルーシー , Rūshī?) is a teenage diclonius girl around 18 years old, Lucy has four vectors with a limited range of two meters.[4] However, she can be swift and lethal within that range, and will use any nearby objects as high velocity projectiles to kill at greater distances. She is also capable of stopping or deflecting most standard ammunition when she concentrates on the task. Lucy hates humans mainly because of how she was treated by her human peers as a child. Consequently, she discounts non-diclonii, claiming they are not real people. She seems to lack empathy, kills without much concern, and acts somewhat sadistically. Despite this lack of concern for human life she will not harm Kohta.
Nyu
Nyuu (にゅう, Nyuu?) is a split personality of Lucy that developed after a .50 BMG round ricocheted off a metallic helmet encasing her head. Nyū has a childlike personality and infantile knowledge of the world, forgetting even that she is a diclonius and how to use or manifest her vectors leaving her a human with horns. She initially lacks spoken language skills; however, she eventually learns a handful of words and phrases. Nyū is innocent and incapable of violent acts, a foil to the normally cold and sadistic Lucy; she is the manifestation of her "good side". When Nyū is attacked violently (or hit on the head), she regresses into Lucy; likewise, when Lucy is treated with love and kindness, she will uncontrollably switch back into Nyū.
Voiced by: Sanae Kobayashi (Japanese), Kira Vincent-Davis (English)
Kouta
Kohta (コウタ, Kōta?) is around 19 years old and enters the story when his cousin's family allows him to move in to their closed down inn in exchange for maintenance while he goes to a local university. Kohta has repressed traumatic memories of his father's and sister's deaths during his childhood at Lucy's hands. Because of his repressing his memories, Kohta does not remember Lucy from when he met her earlier as a child. Due in part to his loss, he has a soft spot for girls in trouble and is extremely generous and protective to the girls around him. He is more forgiving in the anime, but in the manga when he gets his memories back he truly is unforgiving about Lucy killing his father and sister.
Voiced by: Chihiro Suzuki (Japanese), Adam Conlon (English)
Yuka
Yuka (ユカ, Yuka?) is Kohta's cousin.[5] She is also around 19 years old and planning to attend the same university as Kohta. She moves in with him at the inn after having not seen him in many years. Having had a crush on Kohta since childhood, she is in love with him,[6] and is therefore jealous of Kohta's attention to Nyū, to the point of being very irrational.
Voiced by: Mamiko Noto (Japanese), Nancy Novotny (English)
Mayu
A homeless girl who was adopted by Kohta and Yuka. Mayu is generous and caring for everyone, including strangers. Mayu's old parents died and she was soon adopted. Mayu's new father would have her strip for him whenever her mother wasn't home. Mayu ran away from home after a long time of stripping for her father. She was later adopted by Kohta and Yuka.
Nana
Nana is a generous Diclonius, who's arms and legs were unattached from Lucy's vectors. Her arms and legs were immidently replaced with electronic arms and legs. After Mayu finds Nana burning money for a fire, Nana is taken into the inn with Kohta, Yuka, Nyuu and Mayu. When Nana first sees Nyuu, she mistakes Nyuu for Lucy and aggressively attacks her. Nana is told that Nyuu is harmless and has never hurt anyone. Nana realizes that Nyuu is Lucy's split personality, and continues living in the inn peacefully.
Mariko
Kurama
Acasa 
