Kobeni Higashiyama/History

Bat Devil arc
Kobeni was one of the devil hunters accompanying Aki Hayakawa as he saved Denji from the Leech Devil. Aki told her and Hirokazu to evacuate the survivors.

Kobeni was one of the six devil hunters, alongside Aki, Himeno, Denji, Power. and Hirokazu, assigned to the mission of tracking down a devil in the Morino Hotel.

Eternity Devil arc
When Himeno announced that the person who kills the devil will receive a kiss on the cheek from her as a reward, she hugged Kobeni and said that having a reward would be so much more motivating. Inside the hotel, Kobeni followed the others while growing more nervous and muttering to herself. Aki questioned Himeno on the two newcomers and Himeno stated that Kobeni was pretty talented but also timid.

The group encounters what appears to be a walking decapitated head which leads at Kobeni who babbles in fright and can't move. The head is caught by Himeno and sliced in two by Power. As they progress through the Morino Hotel Power threatens Kobeni to test Himeno which causes Himeno to choke Power with her Ghost Devil arm as a warning. When the group discover that they're trapped on the eighth floor of the hotel both Himeno and Aki ask Kobeni to stand still and make double peace signs as they test the limits of the trapped space.

Kobeni begins to panic and worries that they'll starve to death and Hirokazu tries to reassure her by reminding her of why she wanted to become a devil hunter. Power laughs at Kobeni's misery while Himeno tries to calm her down and warns her that fear is a devil's favorite food.

Kobeni ended up breaking down in panic and tried to drink from the toilet. She was subsequently knocked out by Himeno and put in a bed. When the Eternity Devil appears to Denji, Power, Aki, and Himeno and offers them a contract to release them from the hotel in exchange for Denji's life, Kobeni emerges from her room with a knife and demands Denji to let the devil eat him.

She rushes at Denji with her knife but Aki swiftly disarms her and she is knocked down by Himeno who elbows her in the chest. The Eternity Devil laughs mockingly as she's taken down. Later in her paranoia Kobeni begins to blame Power for their current state even though it doesn't line up with her abilities as a Blood Fiend. Hirokazu tries to talk some sense into her but Kobeni accuses him of defending a fiend which must make him a spy for the devils. As they both freak out their combined fear fuels the Eternity Devil who grows and begins to manipulate the space, tilting it while demanding Denji's heart.

Kobeni begins begging anyone to kill Denji. When Hirokazu holds down Denji, Kobeni tries to use her knife to stab him but accidentally stops Aki who dove in the way of her attack. Kobeni tries to claim it isn't her fault and blames Denji for not allowing himself to be eaten. Denji backs up and says he will get eaten, but as part of his plan to fight the Eternity Devil and force it to surrender. Kobeni watches on in shock and horror with the others as Denji transforms and violently cuts himself out of the Eternity Devil's mouth.

After waiting over the course of three days for the battle between Denji and the Eternity Devil to be over, Kobeni sits in the corner in an exhausted state.

Once they leave the Morino Hotel, Himeno orders Kobeni and Hirokazu to report the incident to Public Safety. Kobeni later attends a newbie welcome party for Division 4. She introduces herself, revealing her age and hobby but keeps the identity of the devil she's contracted with a secret. A few other devil hunters comment that her dress is cute.

After the party Kobeni heads home, commenting that alcohol on someone else's tab is the best-tasting alcohol of all.

Katana Man arc
Kobeni was among the devil hunters targeted during the Gun Devil's plot to assassinate to the Special Divisions of Public Safety. An elderly lady pulled out a pistol and shot at her in broad daylight alongside Hirokazu.

Hirokazu was hit in the neck first but managed to shield Kobeni with his body to save her at the cost of his own life. Kobeni was able to kill their attacker and went to save Denji shortly afterward.

As Kobeni appeared on the scene, Akane Sawatari tried attacking her with the tail of the Snake Devil but Kobeni easily evaded it and ran across the Snake Devil's body to attack. She cut off the arm of the Katana Man before he could fire his gun, and caught his weapon out of the air to shoot him in the back. She tried to shoot Akane as well but ran out of bullets and had to take cover behind Denji's body in order to avoid Akane's counterattack. Akane retreated in a van that she loaded the Katana Man onto, leaving Kobeni behind with Denji. Kobeni glanced down at Denji and apologized for trying to kill him before while reflecting on Hirokazu who sacrificed himself for her. As she breaks down, she announces she'll quit as soon as she sees Miss Himeno.

Kobeni took part in the raid against the terrorists led by Akane and was instrumental in capturing her by surprise after she held a knife to Akane's throat. When Aki questioned why Kobeni didn't quit Public Safety like she planned to, Kobeni sheepishly replied that their bonuses were due soon.

Bomb Girl arc
Kobeni attempted to ambush Reze alongside the Violence Fiend. After seeing that the Violence Fiend's attack was ineffective and hearing him tell her to retreat, Kobeni promptly collapsed and claimed that her hip gave out. She frantically apologized to Reze and begged for mercy, claiming that she'd quit her job. Reze resumed her pursuit of Denji, leaving Kobeni to panic.

International Assassins arc
Kobeni and the Violence Fiend went out on a patrol and encountered an unknown devil which the Violence Fiend killed. When Kobeni questioned what type of devil it should be reported as, the Violence Fiend ventured a guess that it was a Grape Devil. They took a break afterward and the Violence Fiend bought Kobeni an ice cream as a treat.

Kobeni tells the Violence Fiend a story from her childhood when she first tried ice cream before commenting that for a Violence Fiend he isn't a very violent person. He agrees with her and explains that it is due to still retaining a lot of his human brain. He explains that he can't remember much except that Makima saved him. Suddenly a man appearing to be Kurose appears in a bullet-riddled car claiming that his partner and master were both gunned down. He orders them to report the incident to HQ and they run off to obey him.

Kobeni and the Violence Fiend are persuaded by 'Kurose' to release him from the hospital and the three of them meet up with the group protecting Denji. Power notices Kobeni's car and asks if it is hers before getting inside of it and demanding a ride. Kobeni nervously tries to stop Power but Power inexplicably drives the car straight into Denji and the assassin impersonating Kurose. Power immediately blames Kobeni for the incident and calls her a murderer, but after it is revealed that Kurose was an assassin she claims all the credit while Kobeni remains miserable inside of her car.

Later Kobeni kneels down by her car to inspect the damage and anxiously worries about how much it will cost to fix the dent.

Kobeni and the Violence Fiend accompany Kishibe outside of the mall where Denji's group is being attacked by the puppets controlled by Santa Claus. Kishibe instructs Kobeni and the Violence Fiend to take care of the remaining dolls in the area while he faces off against Quanxi's fiends.

Inside the department store, Kobeni observes in horror as both Kishibe and Aldo land on top of her car, crushing the roof in and leaving her in shock.

Kobeni and the Violence Fiend are engulfed in darkness like everyone else in the department store when Santa Claus calls upon the Hell Devil to send everyone inside to Hell. After being transported to Hell, Kobeni looks around in shock.

When the Darkness Devil appears and blitzes through the group of devil hunters summoned to Hell, Kobeni has her arms cut off like everyone else leading her to look at her empty sleeves in confusion and horror.

As the Darkness Devil begins slaughtering everyone, the Violence Fiend asks her to take off his mask and hide which she does.

Aki later informed Denji that Kobeni regained her arms and turned in her resignation from Public Safety following the horrific slaughter.

Control Devil arc
Kobeni is revealed to be working as an employee at the restaurant Family Burger after accidentally summoning Chainsaw Man to her by calling for help after being abused by another employee. After two employees are killed by Chainsaw Man, he sits down beginning to yell out incoherently before Kobeni manages to interpret his cries as "Hamburger", and grabs a meal to take to him. She trips, spilling the meal across the floor and Chainsaw Man, only prompting him to cry out louder as another meal is prepared. An employee yells at Kobeni, saying that they were all going to die because of her before being promptly decapitated by Chainsaw Man. Grabbing the second meal to take to him, Kobeni walks forward before falling over and once again spilling the meal onto Chainsaw Man. After a fourth employee is decapitated, Kobeni picks up the bits of the dropped hamburger and hastily re-assembles it before slamming it down onto the table in front of Chainsaw Man.

After Chainsaw Man consumes the smashed burger, he picks up Kobeni with his intestine and walks her out of the restaurant. He takes her to get an ice cream cone, where she states that "It doesn't taste like anything". Then at the request of Chainsaw Man, Kobeni begins to play a game of Dance Dance Mushroom. She gets a perfect score.

After finishing, she turns around to find Chainsaw Man sitting behind her, as well as Makima sitting on the roof of a building across from her. Kobeni tries to deny her involvement in the current events, but Makima tells her that she did have a "great deal" to do with it and that her fear of Chainsaw Man had grown weaker. As Makima aims and fires an attack at Kobeni, a black spear made from Angel's power, Chainsaw Man moves in front of her and pushes her out of the way, with the spear piercing him in her place.

Kobeni ends up in an underground safehouse with Denji and Kishibe. Having witnessed Makima's attack, Kishibe warns her that she will not be able to contact her parents ever again. Kobeni is glad that she finally has a reason to not contact her parents, and breaks down and reveals her fears, telling Denji she is jealous of his regenerative abilities. Denji shares his emotional well-being with Kobeni, as he never had any real control over his life, much to what Kobeni can relate to, being forced to make money in a dangerous job to send her older brother to college. As Denji watches the TV, at people cheering his name, he suffers another emotional breakdown, leaving Kobeni in fright.