Kaoru Sugata is the widowed mother of the protagonist, Sanshiro Sugata. Her husband, Kenichiro Sugata, passed away under suspicious circumstances before the events of the series. Kenichiro was a researcher whose pioneering work laid the foundational technology for the sport of PlaWrestling, and his death is connected to a conflict between his humanitarian vision for the technology and the interests of arms dealers seeking to weaponize it.

In terms of personality, Kaoru initially presents as somewhat aloof and detached. This demeanor creates a narrative contrast with her father-in-law, Kennosuke Sugata, who is portrayed as more critical and traditionalist. However, despite this outward impression, she frequently exhibits moments of profound and unexpected insight. She often attributes these flashes of understanding to her maternal instinct, which allows her to grasp the core of a situation in a way that can offer subtle guidance to those around her.

Her primary role within the story is as a supportive, observant presence in the Sugata household. While she is not directly involved in the technical construction of the wrestling robots or the battles themselves, she maintains a quiet awareness of the family's complex history and legacy. Her motivations are rooted in caring for her son and maintaining the household, doing so in a calm and understated manner. The unresolved circumstances of her husband's death and the potential misuse of his technology form a subtle undercurrent to her character, though she does not typically engage in direct conflict against those who wish to exploit it. She remains a consistently supportive and observant figure throughout the series, with her character defined more by her quiet strength and insight than by a dramatic personal transformation.