Fumika Narutaki attends Mahora Academy in Class 2/3-A as the younger twin sister of Fuka Narutaki. She possesses pink hair, blue eyes, stands 128 cm tall, and weighs 54.3 kg, with measurements of B62-W46-H55. Her birthday falls on December 6 and she has blood type A. Fumika and Fuka are the shortest girls in their class and have not yet begun puberty. Fumika's personality offers a contrast to her twin's mischievous streak. She takes pleasure in cleaning and sweet foods, yet finds hairy or long creatures like caterpillars unsettling. Although she participates in Fuka's pranks, she often voices caution about their potential outcomes. She is a member of both the Strolling Club and the Beautification Committee. The twins share living quarters with Kaede Nagase and assert they receive ninjutsu training from her, frequently donning ninja outfits for activities such as the "Kiss Negi" contest in Kyoto. During story events, Fumika and Fuka spied on Negi Springfield's group planning a trip to England, spreading the news to classmates. They attempted to join the journey by stealing Kaede’s badge but failed. Later, they traveled with Ayaka Yukihiro and toured Negi’s hometown. Following the Magical World Arc, they encountered two animals revealed offscreen as magic princes in disguise during Christmas. In the epilogue, Fumika played a role in saving Nagi Springfield and defeating the Mage of the Beginning. After high school, she married, had a daughter, and settled near Ariadne in the Hellas Empire alongside her sister. Her Pactio card resulted from a botched ritual performed with Fuka; both kissed a copy of Negi simultaneously, creating their shared "Geminae Simulatrices" card. This remains their sole Pactio card across all continuities. In the *Negima!* anime, the card grants ninja attire and shadow doppelgänger abilities. In *Negima!?*, her Cosplay form manifests as a Western detective wielding a magnifying glass artifact that reveals an object’s future. She transformed into a bumblebee during the "Suka incident." Her alternate Armor form "Bansen Shukai" features ninja gear with color schemes inverted from Fuka’s. Trivia notes indicate Fumika achieves high academic grades, though lower than Chizuru Naba’s, and she shares the distinction with Fuka of being the first classmates to marry and have children after graduation.