Mariko Rosebank, formerly Mariko Morinaga, lived as an unassuming housewife until a terrorist bombing killed her husband and young son. The attack inflicted shrapnel wounds, leaving a distinctive rose-shaped scar on her chest that never fades and visibly reddens during intense emotion. This scar earned her the nickname "Marie the Rose," a moniker she adopted and frequently uses for herself. The loss of her family irrevocably changed her path, driving her to enlist in Counterattack Terrorism (CAT), a global counter-terrorism mercenary organization. Despite no prior combat experience, she underwent intensive training, becoming field-ready within a year and rising to lead Division M—an all-female counter-terrorism unit—by age 26. Her rapid progression was noted as improbable, a point later humorously acknowledged in the manga's afterword. Her leadership style centers on a deeply maternal protectiveness towards her unit members, prioritizing their safety on missions whenever possible. This instinct extends to imperiled children, often compelling her to focus on hostage situations involving minors. Her profound hatred of terrorists, stemming from her personal history, remains a core motivator and berserk button. She shares her closest bond with Helga Mittelmeier, her second-in-command; their friendship, forged during CAT training, evolved into a heterosexual life-partnership defined by mutual reliance and concern. This connection is so profound that Mariko, delirious from a head injury, called for Helga instead of her deceased husband. Their dynamic exemplifies a light feminine/dark feminine contrast, Mariko embodying warmth and gentleness against Helga's cooler, more austere demeanor. Operationally, Mariko is recognized for sharp deductive skills and experience, performing "Sherlock Scan"-level assessments to identify terrorist plots. For instance, she deduced an airport exchange involved explosives—not drugs—based on the absence of a second bag and its immediate cargo loading. She also identified a disguised terrorist through gait analysis in video footage. Her command rituals include concluding successful missions with the catchphrase "That's a wrap!"—a habit so ingrained its absence signals unfinished business to her team. Her development involved confronting personal demons, like Gryphon, the terrorist mastermind behind her family's bombing. After achieving vengeance by killing him, she chose to continue leading Division M, acknowledging new threats would always emerge. This resolve underscores her transformation from a grief-driven avenger to a dedicated protector. Her backstory and motivations unfolded across various missions, including a military trial where she defended decisions amid accusations of endangering rookies. She also trained Japanese police officers, highlighting cultural differences in firearm perception. Her character consistently balances vulnerability—manifesting in nightmares and survivor's guilt—with unwavering combat professionalism. This duality culminates in her signature declaration: "I am not afraid of dying. I am afraid of becoming someone I don't want to be."