Fubukimaru Kasuga, a 15-year-old samurai and central figure in the 1995 Crayon Shin-chan film, serves as heir to the Kasuga lineage. Her parents perished at the hands of assassin Matabinekonoshi during their castle's destruction, compelling her to pursue antagonist Unkokusai—who also captured her sibling, Yukino. Guided by a prophecy of "three heroes and one dog" destined to save the castle, she recruits the time-traveling Nohara family and their dog Shiro as allies. Raised as a boy due to her family's lack of male heirs, she maintains a male swordsman disguise despite internal conflict, defiantly declaring "But...I...am NOT a woman!" when confronted about her biological sex. Her true gender surfaces during a hot spring encounter where Shinnosuke Nohara and Shiro accidentally observe her bathing, though she persists in outwardly asserting a male identity. Physically, she possesses long maroon hair tied in a waist-length ponytail, black eyes, and a slender teenage build. An ambidextrous swordmaster, she defeats Matabi in combat and battles Unkokusai's forces until paralyzed by a toxin from Unkokusai's subordinate Ogin, forcing her to entrust her sword to Shinnosuke. Unkokusai's defeat reveals Yukino as biologically male despite feminine presentation, resolving her rescue mission. She exhibits lesbian orientation through her crush on time patrol officer Ring. In the film's closing dream sequence, her mother's spirit urges her to continue fighting, hinting at ongoing struggles. Her journey centers on reconciling inherited duties, concealed identity, and familial loyalty.