Hiyori Munenashi hails from the Outer-District, enduring hardship alone without parental guidance. Her life revolved around relentless daily training, using the Build-Divide system as her path to escape the district's confines. A core drive behind her actions was the ambition to overthrow the King governing the system and secure passage to the Upper-District.

Her path changed dramatically three years before the events of Code White upon meeting Teruto Kurabe and Sakura Banka. Within this trio, she embraced the role of the "kid sister," discovering newfound joy in life. She formally became Teruto Kurabe's apprentice, addressing him as "Master" and developing fierce loyalty towards him.

Following Neo Kyoto's collapse, her circumstances and environment drastically worsened, triggering a stark shift in her personality and outward demeanor. Shedding her former lighthearted and dorky apprentice persona, she adopted a significantly cooler, focused, and resilient attitude to survive the harsh post-collapse reality. Residing with classmates in a hideout, she assumed leadership, demonstrating strategic prowess and determination. Her core objective crystallized: confront the new King's forces and rescue the absent Teruto.

As a Build-Divide player, she wields the white Palhdora as her designated Ace and Territory card in battle. Her skills as a Battle Gamer are central to these confrontations. The narrative traces her evolution from an apprentice into a capable, resolute leader focused on achieving her goals against adversity.