Kei, hailing from the Millenium Science School, is a classic tsundere with sharp pink eyes and long, graceful white hair. Once an advanced AI designed for destruction, she now embodies human emotions in her protective role as an older sister figure. Her loyalty lies with Aris, the "Princess," whom she shields as a vigilant shadow, prioritizing her safety above all else. Striking in her vibrant, field-style jacket and navy pleated skirt, Kei presents a contrast to Aris's innocence with her blunt, caustic demeanor, especially when dealing with the antics of the Game Development Department. Though appearing cold, Kei's deep affection slowly unveils, showing a complex dynamic of irritation and respect toward Sensei. Ever the responsible presence, she remains the steadfast anchor amidst chaos, wrestling with her newfound human emotions and firmly dedicated to her chosen path alongside Aris.