Kunimitsu Tange is a kickboxing coach who encounters Ayane Mitsui after her failed wrestling tryout. Spotting her physical potential, particularly the strength and flexibility of her legs, he attempts to recruit her. His initial comments about her legs cause a misunderstanding where he is mistaken for a pervert. After clarifying, he successfully persuades her to train at his makeshift gym beneath a highway overpass. He also works at a restaurant, often appearing in his uniform or casual clothes like a red t-shirt and brown jacket. Physically, he is tall and broad-shouldered with tanned skin, short black hair, thick black eyebrows, visible wrinkles, and frequently wears dark sunglasses.

His coaching style is strict and demanding, heavily focused on rigorous physical conditioning. He initially deceives Ayane about her training goals, letting her believe she prepares for professional wrestling or mixed martial arts while exclusively drilling her in kickboxing fundamentals. This includes deceptive practices like constructing the training ring to build stamina and focusing drills on kicking techniques. After Ayane discovers the truth following her debut kickboxing match and tries to quit, he refuses to release her. His methods aim to maximize her combat effectiveness, specifically honing her signature "Golden High Kick" as a fight-ending technique. Despite his gruff exterior and occasional social missteps—such as unintentionally grabbing Ayane inappropriately during a match—he shows underlying care, like permitting Kayoko Nakajima to become Ayane’s training assistant to support their friendship.

During Ayane’s pivotal match against Sakurako Miyagawa, he provides corner support, offering tactical advice on countering Miyagawa’s attacks. He participates in the celebration after Ayane’s victory. His relationship with Ayane is defined by mutual friction yet unspoken trust; he consistently pushes her limits to unlock her potential. Though conflicts escalate after his deception is revealed, they reconcile when facing external challenges like Miyagawa’s duel challenge. His role is exclusively confined to coaching, with no broader personal backstory or external media appearances beyond the two OVA episodes.