Akane Minagawa is a central figure in the story, serving as a music teacher at the high school attended by the protagonists Hanabi Yasuraoka and Mugi Awaya. At twenty-three years old, she is a young woman of slim build and average height, with long light-brown hair and hazel eyes, presenting a conventionally attractive and well-put-together appearance that quickly makes her popular among the student body.

Her character is defined by a stark duality between her public persona and her private nature. At school, Akane projects the image of a docile, gentle, and somewhat airheaded young teacher. She is nurturing and kind, a facade that endears her to both students and faculty, allowing her to effortlessly attract the attention of her colleague, Narumi Kanai, by acting clumsy and cute. This performance, however, is a deliberate tool. In her private life, Akane is the complete opposite: manipulative, promiscuous, and deeply sadistic. She actively seeks out romantic and sexual encounters with numerous men, not out of genuine affection, but for the thrill of being desired and the pleasure of watching them become obsessed with her. She grows bored of her partners quickly once they are ensnared, discarding them without a second thought. Her primary motivation stems from a desire to escape boredom and a compulsive need to feel a sense of power and superiority, a pattern that began in her student days when she seduced a friend's crush and discovered the excitement that came from causing another person emotional pain.

Within the narrative, Akane functions as a primary obstacle and a catalyst for the main characters' emotional turmoil. She is the object of Mugi Awaya's obsessive affection, a relationship that predates the series as she was his middle school tutor. Mugi is deeply aware of her true nature, yet this knowledge fuels rather than diminishes his desire for her, leading to a sexual relationship that she uses to further manipulate him. Simultaneously, she becomes a rival to Hanabi Yasuraoka. Recognizing Hanabi's feelings for Narumi Kanai, Akane deliberately sets out to seduce him, taking pleasure in using him to provoke and wound the younger girl. This web of manipulation is the engine that drives the series' central conflicts, as Hanabi and Mugi form their fake relationship in response to the pain Akane inflicts.

The most significant relationship in Akane's life is with Narumi Kanai. What begins as another conquest, a convenient tool to use against Hanabi, evolves into something that disrupts her entire worldview. Narumi is unlike the other men she has controlled; he expresses genuine, unwavering love for her, seeing past her manipulations. When he proposes marriage, she breaks down and warns him that she will be unfaithful, yet he accepts her completely. This unconditional acceptance eventually leads to her own transformation. In the epilogue story Scum's Wish Decor, Akane has married Narumi and become Akane Kanai, and they have a child together. While she still gives voice to her old impulses, claiming she intends to have affairs, her actions prove otherwise. She finds herself unable to go through with betraying Narumi, and in a dreamlike confrontation with her own past self, she finally acknowledges that she has genuinely fallen in love with him and has become fully devoted to her family. Her notable abilities lie not in combat or physical prowess, but in her psychological manipulation, her skill at reading and exploiting the vulnerabilities of others, and her talent for music, specifically the piano.