Yuko

On the surface, Yuko seems to be kind, warmhearted, and sociable. She quickly becomes friends with Asa Mitaka after partnering with her in the Devil Hunter Club, noticing her distress at being shunned by classmates due to Bucky's death. She's very altruistic and friendly, being willing to give out her shoes to Asa so that she wouldn't have to walk home shoeless soon after meeting her, and got upset when Asa gave the shoes back. She dreams of becoming a Devil Hunter to avenge her parents' death, and also because of the wealth it entails. Because of their parents' demise and lack of friends, she empathizes with Asa and grows close to her quickly. According to her, she's unable to understand people and has no friends because of that. She has the personal philosophy that her actions are always justified even if they are mistakes, as long as she thinks that her heart is in the right place. Later, it is revealed that underneath her friendly surface lies a deranged personality with a twisted sense of justice. Yuko's extremely cold-blooded and shows no remorse or concern over killing people she deems evil, all while continuing to smile and act warmly. Her warped sense of morality led her to make an illegal contract with the Fire Devil, who she believed to be the Justice Devil. Because of this contract, she murders her neighbor and attempts to "take care of" Asa's bullying problem. She also knows that Yoru has taken over Asa and how they killed the Class President. She knows all this because she can read minds because of her Devil contract. Despite all this, she still believes herself to be best friends with Asa, and wants to fix her problems for her, even if that requires murder. However, as implied when Yoru asked Yuko regarding the price for her contract with the "Justice Devil", with her supposedly only receiving “a heart that shines with justice", Yuko’s extremely self-righteous behavior regarding her actions and of how she was “just” for murdering the bullies that harassed Asa due to her belief that word of her actions would spread across the nation and dissuade other bullies from bullying others, may be the result of her contract. The actual price for her powers is implied to be that some part of her mind, such as her sense of right and wrong or her sense of Justice, is unknowingly getting altered and radicalized by her devil contract. Later, Yuko is shown to be remorseful for the people she killed, saying she only wanted to be like the Chainsaw Man and had no true noble intentions. She only befriended Asa because she had no friends already. Despite this however, Yuko ended up developing a genuine friendship with Asa.

Yuko is a high school girl of average height. She is a bit shorter than Asa. She has short light blonde hair with a similar eye color and wears dark-colored glasses. She wears the same school uniform as the rest of the girls in her class. The uniform consists of a long-sleeved button up shirt worn beneath a pinafore style dress with a pleated skirt that extends below the knee, a bow at the collar, a wide belt at the waist, and white, knee-high socks. She also wears sneakers. When outside of school, she wears a blank shirt with a dark-colored jacket, light jeans that reach just slightly below the knees, and a pair of sandals.

Devil Contracts
Fire Devil Contract: Yuko had a contract with the Fire Devil, which she believed that was the Justice Devil. Although Yuko tells Asa that she did not pay any price, but having only received "a heart that shines with the light of justice", it is later revealed that the price of the contract is her humanity, which turned Yuko into a Devil. *Mind Reading: The contract allows Yuko to read minds. She can use this power to discover people's secrets and predict their movements in battle. *Sharp Claws: She has sharp claws, which are sharp enough to wound Seigi Akoku's right eye and impale Furio in the chest. *Devil Transformation: The contract gave Yuko the ability to transform into an enhanced form. After surviving the battle against Yoru and Chainsaw Man, she was permanently stuck in a halfway form with traits from both her human and transformed forms.