Asa Mitaka

"I wish... I'd tried living just a little more selfishly."

Аса Митака Asa Mitaka (アサ) is a high school student who became the host of the War Devil, Yoru, being de facto the War Fiend (戦争の魔人).

Appearance
Asa is a high school girl of average build and height. She has brown eyes and black hair that is sometimes colored with a purple tint. Her hair is just past shoulder length and she wears it in two low twin tails. When possessed by the War Devil, her appearance changes somewhat. Her hair is usually worn loose, multiple scars appear across her left cheek and nose, and her eyes have a spiral pattern similar to Makima's.

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 black, knee-high socks. She also wears sneakers.

Personality
Asa is initially a quiet and unsociable girl. She dislikes her classmates, frequently wishing they would drop dead and spurning any offers of friendship, and she would prefer to study over making friends. She dislikes all Devils as a result of her parents being killed by one. Asa later realizes that she was truly jealous of her peers, and wanted to fit in with them as well. She wants to live more selfishly, and to have the things she desired, like friends and a boyfriend. After she becomes the host of the War Devil, gets a second chance at life, and is saved by Chainsaw Man, she is not as negative towards other humans or towards all Devils. She appreciates Chainsaw Man saving her life, but is still willing to work with Yoru in order to defeat him. Despite wanting to live more selfishly, Asa is fairly altruistic, putting herself in harm's way to save others even when she is afraid. She believes that as long as her heart is in the right place, it's okay to make mistakes.

Asa is extremely self-aware that she is a clumsy individual, shown at several important points during her lifetime when she would trip and fall, most importantly when her home was destroyed by the Typhoon Devil and her mother sacrificed herself after Asa fell trying to save a cat. Asa feels guilt and incredible pain of her mother's death and the circumstances surrounding it.

She can also be prone to embarrassment and becomes flustered when dealing with awkward situations, such as when she and Yoshida were partnered up together shortly after Yoru, whilst possessing her, tried to hit on him.

When Yoru is in control of her body, Yoru's personality takes over.

War Devil Arc
Asa is a student attending class at Fourth East High School. She is distant and unsociable to her classmates, many of whom don't even know her name. Asa is further alienated by her class when she accidently trips and kills Bucky the Chicken Devil, a beloved class pet. In an effort to cheer her up, the teacher and class president invite Asa to make amends over Bucky's grave; only for it to be revealed the class president and the teacher have been having an affair. The class president attempts to kill Asa using the powers she obtained from her contract with the Justice Devil. In her dying moments, Asa is greeted by Yoru the War Devil, who will save Asa's life if she shares her body. Asa is resurrected as the War Fiend, Yoru takes over and quickly dispatches her teacher and classmate.

Yoru reveals to Asa that Chainsaw Man attends her school, and that her mission is to defeat him. Being a devil, Yoru doesn't know much of human society so she kept Asa alive by leaving half of her brain intact, the two now share one body. Yoru pushes Asa to join the school's Devil Hunters club in an effort to find Chainsaw Man's true identity, but Asa is bullied and embarrassed by her classmates who still blame her for Bucky's death. She is cheered up by a fellow club member, Yuko, and Asa soon looses focus on finding Chainsaw Man instead opting to enjoy the time she is spending with Yuko. While the two are out patrolling for devils, they are attacked by the Bat Devil. Yoru encourages Asa to kill Yuko and turn her into a weapon so she can fight the Bat Devil, but Asa is unwilling to harm her first friend even if it puts her own life in danger. Asa and Yuko are inadvertently saved by Chainsaw Man, who kills the Bat Devil by accident while fighting the Cockroach Devil.

The next day Yoshida introduces Asa to Denji and reveals he's a Chainsaw Man fan. Denji and Asa get into an argument after Asa admits she did not use to like Chainsaw Man. As their argument escalates, Denji reveals he is Chainsaw Man. Asa doesn't believe him, calls him a loser, and dismisses his claim as nothing more then ramblings from a Chainsaw Man fan.

Asa brushes off the Devil Hunters club to visit Yuko, who was injured during the Bat Devil attack. Yuko admits she doesn't have many friends, and that Asa is the first person to visit her after her injury. In an effort to strengthen their bond, Yuko and Asa reveal their deepest darkest secrets to each other; Asa recounts the time she peed herself in grade school, and Yuko admits she killed her neighbor the other day. When Asa asks why, Yuko says she had discovered her neighbor had been gambling his welfare money away, a fact she learned after making a contract with the Justice Devil and gaining the ability to read minds. Yuko goes on to reveal she knows Asa killed her teacher and class president, and she knowns about Yoru; but she'll keep Asa's secret. Yuko wants to save Asa like Asa saved her, and tells Asa not to come to school tomorrow as she will be taking care of her bullying problem; permanently.

Asa walks home, contemplating what Yuko said. She realizes Yuko is going to kill the bullies at school and wants to go back and talk her out of it, but Yoru wants to battle Yuko and use their fight to lure out Chainsaw Man. When Asa protests, Yoru possesses her and wont give her body back until Yuko is dead. The next morning at school, Yoru confronts Yuko with a katana in the hallway. Yuko reads Yoru's mind and learns of her plan, and tries to convince Yoru that she can't win in a confrontation with her. Yoru only smiles and reminds Yuko that killing her would kill Asa as well. Reluctantly, Yuko transforms into a devil form to engage with Yoru.

Yoru
Yoru resurrected and inhabits Asa's body, turning her into the War fiend, but left half of Asa's brain intact, keeping Asa alive. With the two now sharing one body, Asa was initially overwhelmed with her situation and needed time to accept reality; she eventually agrees to help Yoru defeat Chainsaw Man under threat of permanent death and so long as she gets her body back after they defeat Chainsaw Man.

Because of Yoru's personality, Asa often gets put in awkward social situations, like asking Yoshida to be her boyfriend in an attempt to make him into a weapon. Despite her situation, Asa shows little to no fear towards Yoru. After being briefly intimidated by Yoru, Asa acts very casual towards the War Devil and isn't afraid to talk back or defy the devil if it demands something that she isn't willing to do.

Yuko
Yuko and Asa first met in their school's Devil Hunter Club tryout, when they were assigned to the same group. Asa was originally hesitant to befriend Yuko, mistaking her kindness for pity. However, Yuko explained her belief that she cares more about her heart being in the right place than whether or not her actions are a mistake. Asa quickly grew to like Yuko and said that spending time with Yuko was the most fun she had in a long time. Yuko's belief would have a heavy impact on Asa, who resolved to live her life the same and later refused to kill Yuko and turn her into a weapon for the War Devil. Even though turning Yuko into a weapon would have increased her own survival against the Bat Devil's assault, Asa instead risked her own life to save Yuko.

Denji
Asa and Denji are heavily intertwined, though neither fully knows it yet. Yoru, the War Devil who has taken Asa's body as a fiend, is extremely desperate to kill the Chainsaw Man in order to ignite the seeds of war in the world again, and shows an aggressive and deep loathing of him. Asa, while once holding strong negative feelings to the Chainsaw Man believing him to be a fraud and lumping him with the devil that killed her family, has become more neutral to him. After Hirofumi Yoshida introduced Asa to Denji, they immediately have conflicting attitudes and when Denji reveals himself to be the Chainsaw Man, she disbelieves him and calls him a loser.

Supernatural Abilities
War Devil Possession: After having her body and half her brain taken over by the War Devil, while still retaining her consciousness, the War Devil is able to switch with Asa and gain control of her body. In this state, The War Devil is able to utilize its powers.
 * Enhanced Speed: After becoming host of the War Devil, Asa`s speed is improved to the point that she is able to move very quickly, easily jumping around and dodging attacks from the contracted Class President.
 * Enhanced Strength: After becoming host of the War Devil, Asa`s strength is improved to the point that she isable to pull Tanaka's head off his shoulders and spinal cord out of his body, requiring a great deal of force, and is able to easily carry objects as big as herself with one arm over her head.
 * Flesh Weapons: As a host of the War Devil, Asa is able to use the abilities of the War Devil to manipulate the detached body parts of other people and form them into weapons. This does not appear to immediately kill the victim, as they can still scream in pain even after having their head detached from their body. This seems to only happen when the body or body part is considered a belonging of the War Devil, either after being taken by force via being cut off and stolen, or if someone is devoted enough to the War Devil to make them its belonging.

Skill Set
Swordsmanship: Asa carries a katana as her weapon of choice, suggesting that she is capable of handling it.

Etymology

 * Asa's surname Mitaka means "three" (三) (mi) and "hawk falcon" (鷹) (taka).