Kaoru Sugata is Sanshiro Sugata's widowed mother; her husband Kenichiro Sugata died under suspicious circumstances before the series begins. Kenichiro's research pioneered the foundational technology for PlaWrestling. His vision of using it for humanitarian aid clashed with arms dealers seeking militarization, and his death profoundly impacted the family.

Kaoru appears somewhat aloof and detached, forming a narrative contrast to her more critical and traditionalist father-in-law, Kennosuke Sugata. Despite an outward impression of naivety, she exhibits moments of unexpected insight, crediting them to her "maternal instinct." These observations sometimes offer subtle guidance within the household.

She maintains a supportive, yet background, presence concerning Sanshiro's PlaWrestling pursuits. While not active in his battles or technical work, she possesses a quiet awareness of the family's history and legacy. The unresolved nature of Kenichiro's death and its link to the potential misuse of PlaWrestling technology forms a subtle undercurrent to her character, though she avoids direct conflict against those seeking to weaponize it.

Her character remains consistently supportive and observant throughout the series, without significant development or transformation across official media.