Mina is a young woman who runs a shoe shop in a camp where the last surviving humans live after the near-total domination of the world by the Orphnochs. She inherited the business from her father, who has since passed away. Her mother is not mentioned in the story. Mina lives with a man she calls Ryu, who is actually Takumi Inui living under false memories implanted by Mina's father years earlier. Her father had found Takumi badly wounded after an attack by Smart Brain forces and gave him a new identity to protect him.

Mina describes herself as rough, sloppy, and selfish, and she speaks in a blunt, tomboyish manner. She has never been good at making friends and has lived a somewhat isolated life within the camp. Despite her self-assessment, she possesses a genuinely kind and compassionate nature. She is one of the few humans in the camp who does not harbor blind hatred toward Orphnochs. When many people view the three Orphnochs Yuji Kiba, Yuka Osada, and Naoya Kaido with suspicion and hostility, Mina openly sides with them, stating that they are not just Orphnochs but allies and people just like humans. This stance makes her a target of harassment from other residents of the camp, who give her cold looks and subject her to petty mistreatment.

Mina is motivated by a simple sense of fairness and a desire to see people treated according to their actions rather than their species. She has no grand political agenda and is not a fighter or a member of any resistance group. Her world revolves around her small shop, her daily life, and her care for Ryu, toward whom she develops quiet romantic feelings.

In the story, Mina serves as the anchor for Takumi's amnesiac existence. She gives him a home, a purpose through shoemaking, and a sense of normalcy in a shattered world. Her role becomes pivotal when the human resistance leader Mizuhara attacks Takumi in an attempt to steal the Faiz Gear. Mina, who has just returned Takumi's Faiz Blaster to him and revealed the truth about his past, steps in front of Mizuhara's gunfire to protect Takumi and is fatally shot. Her death is a direct catalyst for the events that follow, as it forces Takumi to fully re-engage with the conflict and sets off a chain of accusations and violence within the human community.

Mina's key relationship is with Takumi, with whom she shares a quiet, domestic bond. She trusts him completely and cares for him deeply, though she never openly confesses her feelings. She also has a protective history with her father, whose decision to save and hide Takumi shaped her life. She interacts briefly with Yuji, Yuka, and Naoya, treating them with kindness when others will not. She has no direct connection to Mari Sonoda or the broader resistance movement before the climax.

Mina does not undergo a traditional character arc of growth or change during the film; she remains consistent in her kindness and moral clarity from beginning to end. Her development is instead revealed through her backstory and her final act of sacrifice, which shows that her gentle resolve was strong enough to cost her life.

In terms of abilities, Mina is a skilled cobbler and seamstress, able to make and repair shoes and clothing by hand. She has some knowledge of sewing and leatherworking, which she uses to run her shop independently. She has no combat skills or supernatural abilities. Her strength lies entirely in her emotional resilience and her willingness to stand by her principles even when it makes her unpopular.