Fujiko Tsubomi, founder and management officer of B.A.B.E.L., champions esper integration. Born to aristocracy in imperial Japan, she defied societal norms for independence. Her father adopted Kyousuke Hyoubu, forging a sibling bond between them. Both espers shared similar abilities and trained together, though Kyousuke initially suppressed his powers. Their lives shifted when they enlisted in the Army ESP Service Corp under Eiji Saotome during World War II.

Fujiko wields multiple esper powers: teleportation, psychokinesis, and psychometry. Honed by wartime combat, her skills rank her among the most powerful espers, rivaling Kyousuke Hyoubu and Hanzo. Despite being over eighty, she maintains youth by controlling body functions through hibernation and absorbing life energy via kissing. This process turned her hair from chestnut brown to off-white, mirroring Kyousuke's aging suspension.

Her personality blends lively adaptability, shifting from playful youthfulness to serious leadership and mischievous teasing. She cares for allies yet exhibits capricious, manipulative, and immature streaks. A self-assured flirt, she openly pursues figures like Minamoto and Shūji Sakaki, using charm to extract information from authorities. Her enduring rebellious nature drives covert guidance. Though holding a grudge against Kyousuke for killing early B.A.B.E.L. members, she retains familial concern for his health and collaborates when necessary.

Her past includes surviving the massacre of their wartime esper unit, fleeing, enduring hardship, and ultimately founding B.A.B.E.L. to realize esper acceptance—contrasting Kyousuke's vengeful path with P.A.N.D.R.A. Later, she supported "The Children" under the codename "The Sleeping Snow White". Key relationships involve her complex dynamic with Kyousuke, whom she views as a brother despite ideological rifts, and Seishiro Uzumi, a fellow esper from their military unit. They shared intellectual and romantic tension that remained unresolved.

During the Black Phantom arc, Fujiko was forcibly awakened from hibernation and corrupted, adopting a cold, cruel demeanor. She separated Minamoto from "The Children," threatened lethal force against them, and exiled Minamoto and Sakaki. After recovering, she resumed her strategic role at B.A.B.E.L., providing critical offensive support in conflicts. Her political acumen was demonstrated through diplomatic missions, such as negotiating with global leaders like the Comerican president.