Dokuro-chan, whose full name is Dokuro Mitsukai, is the title character and central figure of her story. She is an angel who hails from a future timeline, specifically belonging to an organization known as Lulutie, which acts as a committee of angels serving under the authority of God. Her mission from this future is a drastic one: she is sent back in time to assassinate a middle school boy named Sakura Kusakabe. This extreme measure is deemed necessary because, in the future, Sakura is destined to invent a form of immortality that carries a bizarre and offensive side effect, causing all women to stop physically aging at the age of twelve. While Dokuro is sent as an assassin, her initial directive is complicated by her own whimsical nature and personal feelings, leading her to abandon the mission of killing him outright.

In terms of personality, Dokuro-chan is a study in stark contradictions, which is the primary engine of the story's humor. On the surface, she appears as a sweet, cheerful, and incredibly cute girl with a high-pitched, singsong voice and a childlike demeanor, noted for ending her sentences with a unique verbal tic. However, this innocent exterior masks a deeply volatile, impulsive, and short-tempered nature. Her mood can shift in an instant, often triggered by minor misunderstandings, moments of embarrassment, or simple boredom. When displeased, her primary and most dramatic method of expression is to resort to extreme, cartoonish violence, almost exclusively directed at Sakura, who she is supposed to be protecting. This violence is not merely a threat; it is a frequent and gruesome reality, leading to Sakura being bludgeoned, bisected, or otherwise horrifically killed on a regular basis. Despite this brutality, her actions are portrayed as impulsive and lacking in genuine malice, often followed by immediate regret and a cheerful, magical resurrection of her victim. This combination of childish sweetness and unhinged violence defines her role as a chaotic and unpredictable force.

Dokuro-chan's primary motivation evolves from her original mission. After failing to kill Sakura, she instead becomes convinced that she can change the future by distracting and preventing him from ever making his fateful discovery. Her new goal is to protect him from other angels who might complete the assassination, and to keep him so preoccupied with her antics that he never develops the immortality formula. This protective role, however, is deeply ironic, as her own actions pose the most immediate and frequent threat to his life and sanity. She is motivated by a genuine, if twisted, affection for Sakura, having fallen in love with him, which is the primary reason she cannot bring herself to permanently eliminate him. Her role in the story is that of a catalyst for chaos. She is the disruptive element that completely upends the protagonist's ordinary life, turning his home and school into a surreal landscape of magical violence, bizarre clubs, and supernatural occurrences.

Her key relationships are almost entirely defined by her connection to Sakura Kusakabe. He is the focal point of her contradictory affections: she is fiercely devoted to his safety from external threats while being the greatest threat to his physical well-being herself. She torments and teases him sexually while simultaneously punishing him for his reactions. Her relationship with other angels is also significant. She has a complicated professional connection with her fellow angel and rival assassin, Sabato, who is sent to complete the mission Dokuro abandoned. While they have opposing goals, they also exhibit a strange friendship. Dokuro also has a younger sister named Zakuro, who is paradoxically much taller and more physically mature despite being only nine years old. This relationship adds another layer of complexity to her life in the past, as Zakuro is sent to monitor her and Sakura.

Throughout the narrative, Dokuro-chan does not undergo a dramatic moral or personality shift, but her relationship with Sakura deepens. Her violent outbursts remain a constant, but as time passes, she becomes more comfortable and familiar with him, which includes becoming less inhibited about her body and her living situation in his home. Her initial role as a clumsy assassin is gradually replaced by a more settled, albeit still catastrophically violent, domestic chaos as she, Sakura, and eventually other supernatural guests, form a bizarre and dysfunctional family unit. Her core motivation shifts from completing a mission to simply living alongside Sakura and protecting him in her own unique way.

Her notable abilities are as extraordinary as her personality. She possesses superhuman strength and endurance, which causes her to frequently underestimate her own power and accidentally harm those around her. Her signature weapon is a magical, spiked metal club named Excalibolg, with which she performs most of her brutal killings. Her most crucial and defining ability is her power of resurrection. After killing Sakura, she can instantly restore him to full, living health by chanting the nonsensical, whimsical phrase, "Pipiru piru piru pipiru pi". This ability renders her violence consequence-free in the context of the story's comedy. Beyond physical combat and resurrection, Dokuro-chan has also demonstrated other magical feats, such as transforming humans into animals or erasing them from existence when it suits her purposes, usually to further her own agenda with Sakura.