Akira Amami is a young woman who appears as a supporting character. She is a high school student and a determined apprentice to the Oni known as Ibuki, training to fight against the monstrous Makamou. Her path to becoming a warrior is driven by a deep personal tragedy: her parents were killed by Makamou, and her initial motivation for pursuing this dangerous path was a powerful desire for revenge.

In terms of personality, Akira is initially portrayed as serious, driven, and somewhat adversarial. This stern demeanor is partly a product of her dedication to her mission and the trauma she has experienced. She can become annoyed with outsiders who do not understand the gravity of her work, as seen in her early interactions with the protagonist Asumu Adachi, whom she dismisses as a bothersome intruder in a life-or-death struggle. Her master, Ibuki, notes that being confrontational is one of her negative traits. Despite this cold exterior, she is not without kindness, as demonstrated when she gives up her seat to a pregnant woman on a train. Underneath her tough shell, her family is extremely important to her, and the memory of her parents is a constant, driving force that borders on an obsession that she struggles to let go of.

Akira's role in the story is primarily that of a dedicated student and a capable supporter in the fight against the Makamou. She accompanies Ibuki on missions, using her skills to provide assistance. She is a skilled user of Disc Animals, mechanical creatures that can be deployed to scout or aid in combat, and she carries an Onteki, a whistle-like device essential for her training and transformation. Her journey is a parallel to that of Asumu Adachi, as she represents a potential path he could have taken—one of rigorous training and direct confrontation with the supernatural. She briefly achieves a transformed state, referred to by production staff as Transformed Akira, using her Onteki in an attempt to save Ibuki. Her transformed suit was a repurposed version of another Oni's costume.

Akira's key relationships significantly shape her character arc. Her bond with her master, Ibuki, is central; he is her teacher and partner, though his more patient and humane teaching methods often clash with her impatient and revenge-fueled desires. Her relationship with Asumu starts with friction but gradually warms as they come to understand each other. A pivotal relationship is with Shuki, a female Oni who, like Akira, is consumed by a thirst for revenge. Akira is drawn to Shuki, seeing in her a kindred spirit and a path that allows her to embrace her anger. However, Shuki is a dark mentor who is ultimately willing to sacrifice Akira for her own goals, leading to a near-fatal encounter from which Akira must be saved.

This experience is a crucial part of Akira's development. Her obsession with revenge and her impatience to grow stronger lead her down a dark path, causing her to feel stagnant and frustrated with Ibuki's more balanced teachings. The confrontation with Shuki serves as a wake-up call, forcing her to confront the destructive nature of her own hatred. Ultimately, Akira makes the significant decision to give up her goal of becoming a full-fledged Oni. She chooses to step away from the world of combat to protect her memories of her parents and to live a normal human life, finding a new purpose in bringing happiness to others through activities like panel theater performances. Her abilities include proficiency with Disc Animals for combat support and the capacity to use her Onteki for transformation, though this is a brief and early achievement in her training rather than a sustainable fighting form.