"Just you wait, Chainsaw Man! I'll make you vomit nuclear weapons back up!" Yoru (ヨル) is the War Devil (戦争の悪魔, Sensō no akuma) and a member of the Four Horsemen, who now occupies Asa Mitaka’s body as a Fiend. She is the primary antagonist of the titular War Devil arc. The War Devil is only seen briefly in its true form, but appears to have a bird-like body, similar to a dark colored owl or potoo. This weaken form could be the result of Pochita eating most of Yoru’s body after losing to him a long time ago. After taking over Mitaka's body, the War Devil took on her appearance, but with added facial scars across her the center of her face and left cheek, which are in the same location where Mitaka's face was slashed by the Class President. In this form, the War Devil's eyes have multiple rings, similar to Makima, who is another Horseman. Her hair is also usually worn loose rather than in twintails like Mitaka. Yoru wears the school's female student uniform. Yoru is confident and prideful, treating her opponents as mere warm-ups and confidently vowing to take back Nuclear Weapons from Chainsaw Man, contrary to her fellow horseman, Makima, who only thought it was a possibility to win against him. Also similarly to Makima, the War Devil is more than willing to use people for her own goals, forcing Mitaka to work with her under the threat of death. Yoru is very bold and blunt, and will not hesitate to do unusual or embarassing things if they serve her own goals, such as immediately attempting to make Yoshida her boyfriend, embarassing Mitaka, bluntly telling Mitaka about her possession, and demanding that Mitaka kill Yuko for her. This also displays the War Devil's flippant attitude towards death, along with her easily murdering or demanding that others murder people in her stead. Despite all this, Yoru also seems to have a sense of humor and wit - such as in her fight with the class president, where she exclaims "There, a happy ending!" as she intentionally plunges the Tanaka spinal cord sword into the class president in a way to make them kiss. The War Devil is also cruel and holds little sentimental value or attachments to humans, and is mostly uncaring of Mitaka's feelings, as evidenced by her blatant disregard for Mitaka's feeling of friendship for Yuko when repeatedly asking Mitaka to kill Yuko to use as a weapon. However, she did not go through with her threat of killing Mitaka when Mitaka refused to go into school, and she has offered to do "favors" for Mitaka, such as "take care of" the kids who were bullying her and provided the easier name of "Yoru" when Mitaka complained that "War Devil" was too difficult to use as a name. It seems possible that she may have a slight degree of sympathy for Mitaka. Yoru's vendetta against Chainsaw Man also means that she will tolerate anything Mitaka says so long as her goal is ultimately still being worked towards. Unlike Makima, who was almost always calm, composed, and seemingly untouchable, Yoru acts much more "human". She is prone to losing her temper, and became embarassed and angry at being rescued unintentionally by her archenemy, Chainsaw Man. In her anger, she sometimes throws childish tantrums by punching and screaming into the pillows on Asa's bed. In line with this, she also appears more immature and naive than Makima. She takes things at face value, is extremely easy to provoke, and she does not have a good understanding of human society or relationships. She is also worried about losing her power and being forgotten. Her relationship with Asa is more personal than Makima's relationship with Denji.