"Just you wait, Chainsaw Man! I'll make you vomit nuclear weapons back up!"
The War Devil is only seen briefly, but appears to have a bird-like body, similar to a dark colored owl or potoo.
After taking over Mitaka's body, the War Devil took on her appearance, but with added facial scars across 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 also have multiple rings in her eyes similar to Makima’s, another Horseman. Her hair is also worn loose. In Mitaka's form, the War Devil wears the school's female student uniform.
The War Devil is confident and prideful, treating its opponents as mere warm-up and confidently vowing to take back Nuclear Weapons from Chainsaw Man, contrary to its 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.
The War Devil is very bold and blunt, and will not hesitate to do unusual or embarassing things if they serve its goals, such as immediately attempting to make Yoshida her boyfriend, embarassing Mitaka, and bluntly telling Mitaka about the possession situation. The War Devil also has a very flippant attitude towards death, easily murdering or offering to murder people for things ranging from actual crimes to bullying.
As a member of the powerful group of Devils known as the Four Horsemen. They, along with the Weapon Devils once waged a brutal battle against the Chainsaw Devil in Hell, but at the height of the battle, the Chainsaw Devil disappeared, making them unable to find him.
Appearing on Earth, the War Devil took over the body of Asa Mitaka. And after quickly disposing two humans as warm-up, the War Devil vowed to make the notorious Chainsaw vomit back up the Nuclear Weapons Devil who he previously ate.
Enhanced Speed: The War Devil is able to move very quickly, easily jumping around and dodging attacks from the contracted Class President.
Enhanced Strength: The War Devil was able 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 Weapon Creation: The War Devil is able to make anything in her possession, specifically human and fiend, into a variety of deadly weapons almost instantaneously simply by touching them. This does not appear to immediately kill the human, as they can still scream in agony. The weapons created by the War Devil so far are:
- Tanaka Spinal Cord Sword (田中脊髄剣 Tanaka Sekizuiken?): A long crooked sword that the War Devil created using Tanaka’s head and spinal cord that it ripped out of his body. Sharp enough to easily cut through devil-enhanced flesh with ease.
- Flesh Hand Grenade (手榴弾 Shuryūdan?): A hand grenade that the War Devil created using the arm from the contracted Class President. And it is shown that it is able to detonate like a normal grenade.
Contract Creation: As a devil, the War Devil can bestow contracts upon humans for a price. However, The War Devil lost this ability when it took over Mitaka’s body, as a fiend cannot make a contract.
Blood Consumption: As a devil, the War Devil should be able to restore its health by consuming blood.
Body Possession: As a devil, the War Devil could take over a dead human body and their consciousness, becoming a fiend. In this state, they could still use their devil ability albeit significantly weaken. Like all other fiends, the War Devil also has a distinct feature on her head.  That being her facial scars, which only appear while it is in control of the body.
- The War Devil took over the body of Asa Mitaka after her head got sliced in half. The War Devil, however, only took over half of her brain, leaving Mitaka’s consciousness intact while still being able to switch with it to take control over Mitaka’s body anytime it wants. While in this state, whoever isn’t in control of the body will appear as a hallucination to the other and could even communicate to them.
Revival: As a devil, the War Devil should revive in Hell after being killed effectively making it immortal.
Swordsmanship: In the body of Asa Mitaka, the War Devil is a skilled swordswoman. It was able to easily take down the contracted Class President with her sword.
|80. A Dog's Feelings||Absent|
|82. Always Eat A Hearty Breakfast||Absent|
|83. Death, Resurrection, Chainsaw||Absent|
|84. Hero Of Hell||Mentioned|
|85. Bloody Good Gut Feeling||Absent|
|86. Date Chainsaw||Absent|
|87. Chainsaw Man vs. the Horrifying Weapon Humans||Absent|
|88. Star Chainsaw||Absent|
|89. Go Get 'Em, Chainsaw Man||Absent|
|90. Super Power||Absent|
|91. Power, Power, Power||Absent|
|92. Zombie, Blood, Chainsaw||Absent|
|93. You & Crappy Movies||Absent|
|94. Chainsaw Man vs. the Weapon Humans||Absent|
|95. Chainsaw Man vs. Control Devil||Absent|
|96. This Kind of Taste||Absent|
|97. I, Love, Chainsaw||Absent|
|98. Bird & War||Debut|
|99. Two Birds||Appears|
|100. How to Walk Shoeless||Appears|
|101. Afterschool Devil Hunters||Appears|
- The War Devil’s bird-like appearance could be a reference to the little owl that accompanied Athena, the goddess of warfare in Greek Mythology.
- Yoru could be translated as "night" as a counterpart to Asa, which could be translated as "morning".
- Chainsaw Man Manga: Chapter 87, Page 2
- Chainsaw Man Manga: Chapter 98, Page 48
- Chainsaw Man Manga: Chapter 84, Page 11
- Chainsaw Man Manga: Chapter 98, Page 45
- Chainsaw Man Manga: Chapter 99, Pages 17-18
- Chainsaw Man Manga: Chapter 98, Pages 41-42
- Chainsaw Man Manga: Chapter 98, Page 46
- Chainsaw Man Manga: Chapter 98, Page 47
- Chainsaw Man Manga: Chapter 1, Page 13
- Chainsaw Man Manga: Chapter 4, Page 5
- Chainsaw Man Manga: Chapter 99, Page 14
- Chainsaw Man Manga: Chapter 98, Page 40
- Chainsaw Man Manga: Chapter 99, Page 7
- Chainsaw Man Manga: Chapter 99, Pages 13-14
- Chainsaw Man Manga: Chapter 99, Page 5
- Chainsaw Man Manga: Chapter 53, Page 13
|Devils||Angel Devil • Bat Devil • Bomb Devil • Chainsaw Devil • Chicken Devil • Claw Devil • Control Devil • Cosmos Devil • Crossbow Devil • Curse Devil • Darkness Devil • Doll Devil • Eternity Devil • Flamethrower Devil • Fish Devil • Fox Devil • Future Devil • Ghost Devil • Grape Devil • Gun Devil • Hell Devil • Justice Devil • Katana Devil • Knife Devil • Leech Devil • Longsword Devil • Mantis Devil • Mold Devil • Muscle Devil • Needle Devil • Octopus Devil • Pig Devil • Punishment Devil • Sea Cucumber Devil • Shark Devil • Skin Devil • Snake Devil • Spear Devil • Spider Devil • Stone Devil • Tomato Devil • Typhoon Devil • War Devil • Whip Devil • Zombie Devil|
|Fiends||Aki Hayakawa • Beam • Cosmo • Galgali • Long • Pingtsi • Power • Tsugihagi|
|Hybrids||Denji • Katana Man • Reze • Quanxi|