Akio Tademaru was an adult man with short, messy hair and wore glasses. In his first appearance, he was seen wearing a long olive-green coat over a black t-shirt, gray calf-length pants, and brown shoes. His overall appearance reflected a casual yet scholarly persona, fitting for someone deeply involved in Kemono research.

Akio Tademaru initially appeared to be a kind, responsible, and well-mannered adult, presenting himself as a dependable guardian to Shiki Tademaru. However, this image was a calculated facade. In reality, Akio was manipulative, self-serving, and morally bankrupt. Driven by greed and ambition, he sought to exploit Kemono abilities for personal gain, showing no regard for ethical boundaries.

He deceived Kumi Shiki’s mother into participating in cruel experiments under the guise of providing a sustainable future for her and her son. His true goal was to create a hybrid capable of producing golden silk, a substance he believed would secure his fame and establish him as a historic scientific figure. The experiments subjected Kumi to immense suffering, but Akio showed no remorse, viewing the outcome as a scientific triumph rather than a tragedy.

Akio also lied to Shiki about his mother’s condition, manipulating him into believing everything was under control. Calm and patient in demeanor, he consistently deflected inquiries, relying on Shiki’s trust and emotional fatigue to suppress further questioning. His actions revealed a complete lack of empathy, using deception and emotional manipulation to pursue recognition at any cost.

During his time as a student, Akio Tademaru accompanied his older brother on a research expedition into the folklore of Kinshi-Go. During this trip, they encountered a female Arachne Kemono named Kumi Yamagumonoko, with whom Akio’s brother eventually fell in love.

As Akio and his brother continued their research into Kemono, they came to believe that the legend of the Nishikigumo, a mythical spider that spun golden silk was rooted in truth and that the Arachne were the source of the tale. While Akio’s brother was content with having reached this conclusion, Akio saw it as only the beginning. Shortly afterward, his brother died under mysterious circumstances. Akio claimed the death was accidental, stating that his brother had slipped in the forest and succumbed to his injuries. At the time, Kumi was already pregnant with Shiki, Akio’s nephew.

Years later, Kumi sought Akio’s help when Shiki fell ill with the flu, a condition for which there was no treatment in the Kemono world. This prompted her to consider raising Shiki in the human world. Aware of her desperation, Akio offered her an arrangement: in exchange for financial support and access to human resources, she would use her Kemono abilities to generate income. Kumi, devoted to her son’s well-being, reluctantly agreed.

Akio’s true intention, however, was to exploit Kumi in order to recreate the golden thread of legend. Through unethical and inhumane experimentation, he subjected her to forced mating with various forest-dwelling Kemono in an effort to produce a hybrid capable of spinning curative silk. After numerous failed attempts, Aya was born, a child whose threads possessed healing properties. Akio considered her the successful result of his project.

Eventually, Yoko Inari discovered the unethical experiments and blacklisted Akio, preventing him from commercializing or profiting from the golden silk. Frustrated and desperate, he resorted to imprisoning Kumi in a water tank, using her as leverage to control Aya and continue his ambitions in secrecy.

Akio Tademaru is an ordinary human and does not possess any supernatural powers or physical enhancements. His strengths lie in his intelligence, knowledge of Kemono biology, and manipulative tactics. As a scholar, he demonstrates a high level of scientific understanding, particularly in the study and exploitation of Kemono traits for experimental purposes.