Ku Fei, a Chinese exchange student in Class 3-A, balances her vibrant energy with formidable martial arts expertise. Born March 16, 1989, her 151 cm muscular frame, blonde hair, green eyes, and sun-kissed complexion hint at non-Han heritage. Academic hurdles due to limited Japanese land her in the remedial "Baka Rangers" as "Baka Yellow," yet her combat mastery elevates her among Class 3-A’s strongest. Specializing in Xingyi Quan and Bagua Zhang, with training in Baji Quan and Xinyi Liuhe Zhang, she channels raw ki energy—eschewing magic—which limits her against peers blending both disciplines. Employed at Chao Lingshen’s Chao Bao Zi restaurant, her obsession with nikuman dumplings pairs with unwitting service as a test subject for Chao’s gadgets. The Kyoto arc sees her compete for a kiss with Negi Springfield, forging an imperfect Pactio pact. She later mentors Negi under the alias "Ku Roushi," drilling him in ki manipulation to conquer Evangeline’s trials and unlock his magical combat potential. Victorious against Mana Tatsumiya in the Mahora Martial Arts Tournament, she emerges with a magically healed broken arm. Post-tournament, she clashes with Chao over time-travel schemes, culminating in a tearful parting. Joining Negi’s Ala Alba in the Magical World arc, she confronts Fate Averruncus, endures dimensional scattering, and sharpens her skills as a bodyguard in Mundus Magicus. Reuniting with Negi, she tests her growth through an arm-wrestling challenge. Her artifact, the Shinchintetsu Jizaikon staff—a nod to Sun Wukong’s legendary weapon—exemplifies combat versatility. Her arsenal includes the internal-striking Shintokei, defensive Koukikou, and rapid Shundō movement. She withstands robotic foes and counters Shirabe’s sonic assaults through sheer resilience, bypassing magical aid. Persistent academic struggles contrast her martial dedication, cementing her identity as a warrior-scholar in spirit, if not in grades.