|“||When I cut things or people, I feel like I’ve gotten that much stronger! The tougher or harder the opponent is, the better I feel, amigo! There are things nobody’s ever managed to cut before, and I—or rather we, Murasámia and I—are going to cut them! That’s unbelievably fun!||”|
Maria Barcelito (マリア・バルセリート, Maria Baruserīto) is a katana-wielding Mexican assassin working for the Gandor Family.
Maria is a beautiful woman who is often mistaken for an actress. She has brown hair that she ties up in a ponytail, accentuated with a rose accessory. She wears vibrantly colored clothing, an unusual trait for assassins. By her side she keeps her two samurai swords "Murasámia" and "Kochite".
Maria has a childlike personality despite her womanly looks. She is often flamboyant and dramatic in her actions, and tends to get highly carried away whenever she is fighting someone else. She loves her blades and jumps at any chance to slash something or someone.
She suffers a major crisis in confidence when she fails to defeat Adele in 1933, completely losing faith in her abilities. Thanks to Tick Jefferson's efforts, she regains her confidence and natural cheerfulness.
Maria has a habit of referring to others as amigo or amiga.
Maria grew up in a village in Mexico, born to a pair of skilled assassins who died when she was an infant. She was raised by her grandparents in their stead.
One day in September 1925, Maria is playing around with one of her grandfather's katana when she accidentally slashes his arm. He is delighted rather than angered, and he decides to train her in sword fighting, telling her that there is nothing in this world that her katana cannot cut. She is devastated when he passes away, since she had promised that she would kill him with his katanas.
During her childhood, she often spars with her friend Elita.
Maria pursues the assassin profession upon entering adulthood; her first target is Mr. Maloney, whose assassination is witnessed by the politician Manfred Beriam. She remarks upon how calm Beriam is despite the murder—unaware of who Beriam is—and wonders out-loud what she ought to do now that he has seen her face.
Beriam points out that no-one would believe his testimony, and deduces that this is her first kill from the way her hands are shaking and the dilation of her pupils. He concludes that she has the predisposition to be a 'crazed killer', since she's not only shaking from fear but excitement. Beriam says that he will put Maloney's death to good use.
The next day, Maria sees Beriam's picture in the paper alongside a statement that he saw a local mafioso kill Maloney. She later relates this incident to an unknown individual.
(To be expanded on)
Maria is one of several assassins hired by Runorata Family capo Gustavo Bagetta to raid the Daily Days headquarters in January. She participates in the climactic battle at the information brokerage and is defeated by Claire, who mocks her beliefs and skills both. Keith Gandor defends her, and in the aftermath of the incident, Maria joins the Gandors as their guest. Eventually she elects to work for the Gandors, partly out of fear and respect for Keith.
Six months later, she and Tick meet Mark Wilmens in Coraggioso.
1933—The Slash 
In September 1933, Maria is chastised by Luck Gandor for having destroyed Coraggioso property while guarding the jazz hall's dancing girls. Frustrated, he orders her to act as Tick Jefferson's bodyguard while Tick engages in negotiations with Jacuzzi Splot, whose gang has been operating on Gandor turf. Maria accepts the job, eager for a chance to hone her skills. She and Tick briefly discuss their respective interests while the latter cuts flowers, before leaving Coraggioso.
During their walk to the Genoard Family manor on Millionaires' Row, Tick talks about his falling out with his younger brother and why he hurts people. He is aware that he will probably be hurt in turn some day, and Maria swears to protect him.
Caught up in conversation, they accidentally pass the mansion and are forced to enter through the back door of the Genoard estate. There, Maria is confronted by Chané Laforet, and the two women fight until they hear Jacuzzi scream from inside the mansion. Chané disappears into the mansion; Maria follows her while Tick heads for the front door.
Inside the manor, Maria severes Dallas Genoard's hand when he threatens Tick. She is shocked and delighted when his hand regenerates, and proceeds to slash him over and over again. Angered, Tim orders Adele to stop Maria.
The two women clash, and Maria's confidence takes a heavy blow when Adele challenges her skill and belief in herself. Adele inflicts several wounds on Maria over the course of the fight, and their duel is only ended when Ronny Schiatto impatiently vanishes their weapons from their hands. Maria is dejected, having lost the chance to redeem herself. Nice Holystone sets off a smoke bomb, and in the ensuing confusion Tick grabs Maria and runs.
Tick and Maria take refuge from the fierce rain in a dirty, dusty old building, and Maria huddles against a wall, devastated by her defeat. Tick attempts to console her, and she apologises for not protecting him better. With the mission a failure, the two decide to report back to the Luck Gandor after the rain lets up.
The next day, the two stop by the Genoard manor on the way back to the Gandors. Maria is greeted by Eve Genoard at the front door, who recognizes her from the Daily Days raid. Maria takes Eve and her cook Fang Lin-Shan hostage, and demands that Fang lead them to Jacuzzi's hideout.
The factory hideout turns out to be empty when they arrive, and Maria advances toward Fang as if to stab him. Chané comes to Fang's rescue. having arrived at the factory with Claire. Claire recognizes Maria from the raid and asks her why she is still weak, causing her to lash out. Tick calms the situation down, and they ally with Eve to find Dallas and Jacuzzi at Mist Wall, a large skyscraper owned by Nebula.
The six of them walk to the Mist Wall together, and head up to the Babel Restaurant on the top floor. Maria is plagued with doubt upon finding Adele there, but with Tick's encouragement she rises to the occasion and challenges Adele to a fight. Adele dismisses Maria as an inadequate opponent—only to be defeated by Claire, triggering her inferiority complex. Maria intervenes before Adele can kill Jacuzzi.
With her confidence back, Maria manages to defeat Adele in combat. Elated, she raises her sword to the skies and declares that she too can cut God, prompting the sky to open amidst the rain.
Maria and Tick carry Tim and Adele to a doctor in New York, and return to Coraggioso. Tick has a long private talk with Luck, and when she enters Luck's office Luck berates her and Tick for failing to report back—he had to hear the story from Ronny first. He coldly informs them that he will not be paying them, and suggests they sell their information to the Daily Days if they want money.
The two of them head out to the Daily Days, and Maria is sure that she and Tick will continue to be together, be it as friends or as a couple.
In February, the Gandors hire several assassins as muscle for the upcoming Runorata casino party at Ra's Lance, including Maria, Ladd Russo, Graham Specter, Laz Smith, Mark Wilmens, Alkins, and one other yet to be identified person. On the first day of the party, Maria and Tick are the only two to accompany the Gandor brothers—the rest of the assassins are ordered elsewhere on the premises.
Maria wields two katanas: Murasámia and Kochite, both of which she treasures deeply since they once belonged to her grandfather. While she has a natural affinity for sword fighting, much of her skill comes from training with her grandfather and extensive sparring experience. Her strength is said to be highly valued by Gandor Family employees, and even Claire Stanfield comments that she has the potential to be stronger if she shows more devotion to her skills.
- Maria's childhood friend Elita has a supporting role in the audio drama Firo Prochainezo Witnesses the 53rd Death of Pietro Gonzales, in which she tricks Pietro and Dominico and later imprisons Firo Prochainezo.
- Elita shares Maria's habit of calling others amigo or amiga (friend).