Kei Hanabusa, a second-year student at Urawa Hosei High School, plays a vital role on the girls' soccer team as their primary scout and strategic analyst. She possesses short black hair, neatly styled and often parted to the side, complemented by round glasses. Her consistent attire includes the Urawa Hosei tracksuit featuring the school's green and white symbol, a red star pin, and a blue handkerchief typically worn around her neck.

Her core strength lies in meticulous analytical skills, dedicated to observing rival teams, gathering detailed information, and formulating precise game plans by pinpointing opponent movements and tactical weaknesses. A significant lapse occurred when her pre-match scouting report underestimated Warabi Seinan player Nozomi Onda. Kei described Onda as "like a statue" due to minimal movement and perceived lack of threat, causing her team to lower their guard. This miscalculation contributed to unexpected challenges for Urawa Hosei during the match.

Kei maintains a close working relationship and mutual respect with teammate Chika Kirishima, frequently collaborating on scouting missions. She is notably protective of Chika, especially against external criticism. When coach Masahiro Gotōda blamed Chika for a prior loss to Kunogi Academy, Kei passionately defended her, recalling Chika's diligent efforts during the critical Warabi Seinan match. This defense revealed Kei's deep emotional investment, as she became visibly moved—removing her glasses and nearly crying.

Characterized as serious, intelligent, and methodical, Kei prioritizes accuracy and thoroughness in her duties. However, she can become emotionally reactive when her friends or team are involved, her usually focused demeanor shifting during high-stakes interpersonal situations. She attended a practice match between Warabi Seinan and Kunogi Academy alongside Chika Kirishima but departed after the first half.