Youko Nanase, born Youko Chigi, is the mother of Takeshi and Gekkou Nanase. Once a revered member of Wizard Brace and ranked within the top fifteen magicians of the First Great Magic War, she wielded the legendary Twilight blade in pivotal battles that shaped history. Sixteen years later, her role as a mother fractures following an unresolved incident between her sons, leaving her relationship with Takeshi icy and detached.

Her fall from power stemmed from an encounter with Ghost Trailer’s enigmatic leader, which stripped her of magic and cast a shadow over her life. Secretly aware of a critical accident involving her sons, she buried the truth from Takeshi. Fearing Gekkou’s potential metamorphosis into Kazuma Ryuusenji—the war’s looming antagonist—she engineered a staged accident to eliminate him. The failed plot intensified family fractures, provoking Gekkou’s lethal retaliation, thwarted only by Kazuma’s intervention.

Before her decline, she taught at Subaru Magic Academy, her influence lingering through enduring connections in magical circles. Though no longer active in current conflicts, her past choices haunt her sons’ turbulent rivalry. Her name, derived from characters meaning “light,” “sun,” “male,” and “child,” contrasts her surname’s amalgamation of “seven” and “swift current.” Visually, she carries a weary, listless air, with black hair, piercing purple eyes, and a demeanor etched by the weight of buried truths and vanished power.