Barbara is a central figure in the manga of the same name, appearing first as a young woman living on the streets of Tokyo. Initially presented in a state of profound degradation, she is described as filthy, perpetually drunk, and living as a vagrant, having been reduced to selling her body to survive. Her introduction is harsh, framing her as an outcast of a society that discards its vulnerable members.

Despite this squalid existence, Barbara possesses a sharp intellect and an unexpected cultural sophistication. She is capable of quoting the works of French poets such as Paul Verlaine, a detail that immediately distinguishes her from a common beggar and intrigues the successful novelist Yosuke Mikura. Her personality is volatile and challenging; she is at once a drunken, disruptive presence who shows little regard for social norms or tidiness, and a figure of enigmatic allure. Her behavior is often self-destructive, and she seems to drift through life with a mixture of nihilism and a strange, magnetic vitality.

Within the story, Barbara serves primarily as the muse and live-in companion to Mikura, who becomes fascinated by her and invites her into his home. Her role is deeply ambivalent: she acts as both an inspirational force that unlocks his creative potential and a parasitic, destructive influence that contributes to his downward spiral into madness and violence. She is the catalyst for much of the plot, and her mysterious nature is a central driver of the narrative's tension. The story suggests that her function as a muse is not unique to Mikura; an African writer and political activist named Russalka, who has a past with her, reveals that she inspired him in the past and that her departure left him unable to write. This establishes a pattern where Barbara elevates the artistic output of those she attaches herself to, only to eventually leave them in despair.

The relationship between Barbara and Mikura is the core of the manga. It is a toxic and co-dependent bond characterized by violent altercations, with Mikura physically abusing her, followed by reconciliations and periods of intense creative output. He enables her alcoholism, while she inspires his most successful writing. Despite the abuse, she occasionally acts as his savior, protecting him from public disgrace or the consequences of his own delusions. The nature of Barbara herself remains ambiguous; she is implied to be a supernatural entity, perhaps a modern incarnation of a classical muse. Her name and her mother's name, Munemoshune, are evocative of Mnemosyne, the Greek goddess of memory and mother of the nine muses. Her true nature as a real woman, a hallucination, or an immortal spirit is never definitively resolved, adding to her enigmatic quality.

In terms of development, Barbara is less a character who grows and more a constant, disruptive force whose presence causes change in others. Her own past is revealed in fragments, showing a history of moving between artists, but her core personality remains fixed. She is an agent of chaos and inspiration, and her motivations are inscrutable, seemingly driven by a need for alcohol, freedom, and proximity to artistic creation. Visually, she is noted for her distinctive eyes, which are often drawn with an x-mark in the pupils, a stylistic choice that reflects the nihilistic themes of the era and Tezuka's artistic experimentation. She does not possess superhuman abilities in a conventional sense, but her power lies in her seemingly supernatural capacity to profoundly influence the creative and mental state of the artists she chooses to inhabit. This ability to act as a living embodiment of inspiration, with all its ecstasies and terrors, is her defining and most notable trait.