Asuka Mishima, a classmate and former girlfriend of Haruto Kirishima, sports short black hair with forehead-obscuring bangs and striking sea-green eyes. Her appearance echoes Suzuka Asahina from the creator's earlier work. Hailing from Fukushima, she intermittently lapses into regional dialect when excited and harbors self-consciousness about her breast size, frequently measuring herself against other female characters. Initially abrasive and combative, she once subdued Haruto with a baseball bat after misidentifying him as an intruder. Over time, she warmed to him, evolving into a close friend and neighbor of his older sister Aoi.

Romantic feelings for Haruto emerged, leading her to become his girlfriend after Yuzuki Eba's departure from Tokyo. Compassion and forgiveness define her personality; she overlooks Haruto's compromising situations—like being spotted leaving a love hotel with another girl—without pressing for explanations. She sought to deepen their bond by planning a trip together, but Fukushima family duties postponed it.

Their relationship dissolved when she surprised Haruto in Hiroshima and found him at a summer festival with Yuzuki, who confessed her feelings to him. Heartbroken post-breakup, Asuka eventually moved forward and forgave Haruto.

Beyond the main series, she resurfaces in the creator's subsequent works. In *Hitman*, she achieves success as a softball player and anchors a story arc where protagonists craft a manga about her love life. A bonus manga in *Princess Lucia*'s final volume discloses her dating a Hiroshima Carp baseball team member.

Her surname originates from the Mishima family in the *Tekken* series, while her character design and name evoke Asuka Kazama from the same franchise. She secured fifth place in both of the series' character popularity polls.