Asaka Takatō is a significant figure in the backstory of the series, appearing as a key character in flashbacks that explore the protagonist's past. She is a young Japanese woman who was hired to work at a mysterious research facility known as the National Institution for Advanced Biosciences. Struggling to find a job, she accepted the position without a full understanding of her assignment, which led her deep into an underground shelter within the facility. There, her task was to care for a young boy who was referred to by the designation Alpha Omega, a child the other staff members feared and avoided due to his extraordinary and lethal powers. Unlike the other researchers, Asaka chose to treat him as an ordinary child. She gave him the name Yogiri, and he would later take her surname as his own, signifying the deep bond they formed, despite having no blood relation. Her decision to name him and act as his foster parent had a profound and formative impact on his personality development.

In terms of personality, Asaka initially experienced fear upon learning about Yogiri's abilities, but this feeling quickly gave way to self-directed frustration and anger once she saw that he was, in her eyes, just a normal boy. This shift reveals a core aspect of her character: a strong sense of personal responsibility and a compassionate nature. She is outgoing and encouraged Yogiri to be more active and playful, trying to provide him with a semblance of a normal childhood despite his confinement. Her motivation for taking the job was partly rooted in a practical dislike for job hunting, but her actions demonstrate a deep-seated commitment to her role as a caretaker, evolving into a genuine maternal affection for the child in her charge. Her greatest strength lies not in any special power, as she is a completely normal human without any abilities of her own, but in her unwavering and normalizing presence. The central conflict in her role arose when she was kidnapped by an organization, forcing the young Yogiri to use his powers to rescue her, a pivotal event that solidified her acceptance of his true self.

Asaka's primary and most crucial relationship is with Yogiri, whom she raised and protected. She serves as his surrogate mother and guardian, a role that defines her entire existence within the narrative. Her interactions with other staff members at the institute, such as her supervisor Yukio Shiraishi, were primarily professional, as she navigated the unusual and secretive environment of the research facility. Asaka's character development is central to her purpose in the story. She transitions from being a new, perhaps naive, employee to a dedicated and courageous maternal figure. Her journey is one of overcoming fear and societal expectation to accept and love a child who is inherently dangerous, which in turn shapes Yogiri's own moral compass and humanity. She is an original character created for the light novel and subsequent anime adaptation, not appearing in the original web novel, which underscores her specific narrative importance as the emotional anchor for the protagonist's past.