Madoka Kyōno hails from the coastal town of Kamogawa and attends Kamogawa Girls' High School. She founded the Jersey Club as its sole initial member, dedicating herself to assisting other school clubs and community members. This drive stems from a deeply ingrained desire to help others, inspired by her childhood admiration for her cousin Youko, a former Jersey Club member. Ten years prior, Madoka's mother drowned during a rescue attempt; Madoka nearly drowned as well, an event during which she first encountered the robotic aircraft Vox Aura, later pivotal to her story.

Relentlessly optimistic and energetically enthusiastic, Madoka often prioritizes others' needs over her own commitments, leading to overwhelming situations. She exhibits Chronic Hero Syndrome, intervening unprompted in crises from rescuing drowning individuals to confronting interplanetary threats. A distinctive verbal tic involves her saying "Maru" while tracing a circle in the air upon completing tasks. Academically, she struggles, particularly in mathematics, but excels in physical activities like kendo, wrestling, and competitive swimming—the latter proving vital in rescue operations.

Madoka pilots the Vox Aura, naming it "Midori" for its green coloration. Her natural aptitude allows rapid mastery of its controls, including transitions between flight and combat modes. Initially activated to defend Kamogawa from extraterrestrial threats, her piloting evolves to address larger conflicts, though it inadvertently triggers catastrophic events. The Vox Aura's activation correlates with her emotional state; it ceased functioning after a traumatic incident but reactivated through percussive maintenance linked to her determination.

Her relationships form the core of her development. She bonds intensely with Lan, an alien princess from Le Garite, and Muginami, a refugee from De Metrio. Both join the Jersey Club and co-pilot Vox units. Their friendship withstands political tensions between their home planets, reinforced by shared experiences including a three-way kiss orchestrated by Madoka. She resides with her uncle Hiroshi, who operates a local restaurant, and maintains close ties with Youko, who researches the Vox units' mysteries. A "Freaky Friday" body swap occurred between Madoka and Yurikano, a figure from Le Garite's history, during a neural synchronization experiment, though they reverted within an episode.

Across the series, Madoka confronts escalating challenges. In Season 1, she grapples with Lan and Muginami's departures amid interstellar warfare, culminating in an emotional breakdown during their farewell. Season 2 explores her unresolved future plans as a high school senior, juxtaposed with ongoing Jersey Club activities and support for Hiroshi's beach café. She inadvertently activates the cosmic phenomenon Rinne twice—first causing widespread destruction, then nearly annihilating Earth—prompting her to deliver gut-punching rebukes to the warring planetary leaders. Her journey concludes with her receiving direct communication from the United Nations Secretary General, acknowledging her role in resolving the conflict.