|First Appearance||Chapter 40: Buccaneer|
|Last Appearance|| Chapter 59: (in person)
Chapter 61: End (in dream) Chapter 61.5 extra (breaking 4th wall)
|Hair Color||She is seen with blonde and violet hair and can transform.|
|Height||Over 7 feet|
|Parents||Dr. Naomitsu Madaraki (creator)|
|Sibling(s)|| Fran Madaraki
She is first met by Veronica under the guise of being the Professor. She easily tears Veronica apart and leaves her for dead as she wanted to draw out Fran and take the estate. Fran is able to revive Veronica and places her in a new body as Gavrill sends her gang into the hotel to find and exterminate them, allowing them to kill civilians as well. Fran and Veronica fight back and are able to escape by bombing Gavrill in the hotel but she survives while in her transformed state.
She is later show in chapter 44, having survived the bombing and visiting Dr. Amatsuka for her checkup. She acts very curt and vulgar around him but she seems to genuinely care for the old doctor, and seeks to get revenge after he was attacked by American agents acting behalf on American politicians. She kills a small town politician named Frazel before making a warning to a Senator Barry that he's next. Fearing his demise, he seeks Fran for safety at the estate, lying to her about not knowing why she's after him.
After being led to an isolated island, clones of Rumiko Kahou emerge from the forest in an attempt by Fran to subdue Gavrill. The clones are slaughtered effortlessly but Fran hopes that Gavrill's bloodlust will cool down as she goes through the clones.
In chapter 49, Gavrill takes the role of substitute teacher at the request of Dr. Amatsuka. Fran is present for the time Gavrill is subbing for Dr. Amatsuka and tries her best to avoid her. After telling some students who were fighting to stop, they take offense and try to ambush her after school, but she knows who they are and not being allowed to kill them, she gives them advice on how to rape their classmates. The boys are taken aback and keep quiet in the days following. She creeps out some girls by telling them school is useless and they can just pay their way into college and get cushy jobs through their connections or if they're poor then they can get knocked up by a rich guy and marry them before killing their husbands to secure an inheritance, much to the girls' chagrin.
She gives advice to a bullied homicidal-suicidal student that living successfully is a better revenge or recording their shenanigans and blackmailing them in the future if the bullies become successful is a better way. Her advice seems to resonate with some students and she is seen as popular by the other students and her reputation as "cool" spreads as a result.
Despite hating the students and the job, she agrees to continue subbing for 6 more months after unloading on Dr. Amatsuka. She accompanies a group of her students in a fight with a rival school and single-handedly takes down the entire rival school's thugs and knocks out a few of her own students in the fray. She becomes the go to for petty advice for her students but they seem to hold it dearly as Gavrill is blunt and honest unlike other adults who lie and abuse the students.
Armed intruders show up and Veronica accuses Gavrill of being behind it, but it quickly turns out that it's not the case and they team up to fight them off.
Teaching as a sub again at the request of Dr. Amatsuka, she is present the day 16 year old student and friend of Veronica, Hotaru Miyake, is murdered and leads Veronica on, telling her she knows who killed Hotaru. Telling her that she'll only tell who did it if Veronica agrees to be her slave, Veronica gets on her knees to beg for info as Gavrill looks sympathetic and tells her that the begging was enough. She reveals that she could smell that 5 people, including Hotaru, were in that room before the murder occurred, 2 of them bodyguards and 2 of them party members of a politician who recently visited the school and they had gang-raped Hotaru and choked her to death accidentally. She also reveals that Hotaru was the sex slave of the school's principal. However, she forbids Veronica from getting vengeance and ensures Fran knows that she'll come after her if Veronica kills or reports anyone involved since she wants Veronica to suffer. Unbeknownst to Gavrill, Hotaru had planned on infecting all her rapists and abusers with super gonorrhea which leads to the school's boys' sports teams, several teachers and coaches, the principal, local policemen and politicians becoming severely ill and implied to be killed shortly after.
In the final chapter, Gavrill appears in Fran's oxygen deprived dream and is still hostile towards her but Dr. Amatsuka tells her to keep him company so Gavrill behaves. Fran asks herself how they know eachother, as she's never seen them interact in person before. Gavrill dances with a fearful Veronica in Fran's dream.
In chapter 61.5, Gavrill is being interviewed along with her younger sisters. She wishes she had more screen time which Veronica is surprised she received any at all for being so vile. They begin to argue as Fran tries to calm them down. After bringing up how Veronica's actions led to Aslam's death and she hasn't paid for it, she tries to shift the focus on Gavrill for killing her but Gavrill says it doesn't count since she was revived by Fran. Both older sisters begin a tirade of attacks on Veronica as Fran says she'd too dependent on her and Gavrill mocks her for not knowing who killed her friend and how she ruined the roach city. She begins to cry as Fran hugs her telling her she really loves her and Gavrill pats her on the head saying she was just joking.
She is usually seen sporting leather jackets, leg splints and arm braces and a pair of headphones with timers on the side that seem to allow her to control her transformation abilities.
She is very vulgar and does not hesitate to speak like a sailor.
According her own words, she is immune to biological agents.
Her nickname is derived from her transformation; a grotesque wolf like creature. She can modify her body in numerous other ways as well, such as hardening muscle in a localized region to deflect bullets or sword slashed as seen when Veronica first meets her.
She seems to genuinely care for Dr. Amatsuka's well being. However she appears to despise Dr. Naomitsu Madaraki.
She has a keen sense of smell and can tell when people are hormonal, angry, scared, dead, ect...