Yuko

Yuko (ユウコ) was a high school student and member of the Devil Hunter Club alongside Asa Mitaka and Hirofumi Yoshida. She had a contract with the Justice Devil.

Appearance
Yuko is a high school girl of average height. She is a bit shorter than Asa. She has short, light-colored hair 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.

The contract with the Justice Devil makes her capable of transforming herself into a thin and gaunt being with an uncovered brain and tentacles instead of legs.

When she's resurrected following her first death at the hands of Asa, Yuko comes back as a gigantic monster with the head of her transformed form surrounded by tentacles. In this form, she's big enough to cover several floors of the school with her body.

Personality
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 Justice Devil, murdering her neighbor and attempting 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 as she is now in a contract with a devil.

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 the Justice Devil.

War Devil arc
After being paired in the Devil Hunter Club, Yuko introduces herself to Asa, and says she is a big fan of Chainsaw Man. After school, Yuko comes running out with one shoe off, saying she will share one of hers with Asa. Asa refuses the kind gesture, but Yuko makes her chase her throughout town to give it back. The two of them end up at Yuko's house. Yuko sees Asa off, giving her both shoes.

The next day, Yuko and Asa walk to the city hunting devils while discussing things about them. They reveal to each other that both their parents were killed by devils, which excites Yuko and makes her think the two of them are like devil hunting avengers in a manga series. They wander around the city attempting to locate a devil, when they suddenly come across the new Bat Devil attacking. Yuko and Asa make a run for it, but the Bat Devil's enormous size causes the building they're in to collapse around them. Yuko is injured with a pike in her ankle.

Later, Asa goes to Yuko's house, and they sit with each other telling secrets. Yuko confesses that she killed her neighbour, offering to show Asa the body. Yuko then reveals made a deal with the Justice Devil, granting her the ability to read mind in order to be able to understand those around her and to help Asa, and as a result she is aware of Yoru and the cause of death for both Tanaka and the previous class president. Yuko decides she will "handle" Asa's bullying problem and tells her not to come to school tomorrow.

Yoru arrives at the school and confronts Yuko, who uses the power given to her by the Justice Devil to transform and attack her. They start their fight, but Yuko is able to read all of Yoru's movements. She attacks several students who she believes are "bullies", while Yoru and the members of the Devil Hunter Club are unable to defeat her. Asa tells Yuko what she is doing is wrong, but Yuko rebuffs her by saying that by killing bullies as a Devil here, other bullies throughout Japan would be afraid. With the power of the Justice Devil, she can become a symbol like Chainsaw Man. Yuko also reveals that the Justice Devil asked nothing in return for a contract, only gave her a "heart" that shines with justice. Asa strips off her uniform and turns it into a sword. She slashes at Yuko's legs and Yuko is torn apart into many pieces. A woman then arrives and says she can bring Yuko back to life. As Devil Hunters arrive at the school, Yuko, who has grown tremendously in size, bursts out through the school, destroying most of it.

She is confronted by two Devil Hunters, who she easily kills. Yuko notices Asa passed out, and blames an innocent bystander for this. Denji arrives and transforms into Chainsaw Man, saving the girl. He attacks Yuko and overpowers her with his blades. Yuko tries to read Denji's mind to get an advantage over him, but finds out that he isn't even thinking of the fight, only how to expose his secret identity while making it seem natural. Denji then kills Yuko.

Devil Contracts
Justice Devil Contract: Yuko has a contract with the Justice Devil for an unknown price. The contract allows Yuko to read minds and transform to obtain an enhanced form.

Weapons
Her weapon of choice against Devils is a hatchet, similar to the one Denji used.

Etymology
Like most characters, Yuko's name is written in katakana instead of kanji. However, the name Yuko can have many meanings depending on the kanji it is written with. One writing, 夕子, means "evening child", which fits with Asa and Yoru's names meaning "morning" and "night".