Born third to Enji and Rei Todoroki within a Quirk Marriage designed to surpass All Might, Natsuo Todoroki shares the family's tumultuous legacy. He stands alongside siblings: eldest brother Toya, older sister Fuyumi, and youngest brother Shoto. Like Fuyumi, Natsuo inherited only his mother's ice Quirk, Frost, marking him a "failure" to Enji and resulting in severe childhood neglect. This exclusion intensified after Toya's near-attack on infant Shoto, leaving Natsuo forbidden from interacting with his youngest brother and ignorant of even Shoto's favorite food. He witnessed Enji's brutal training of Shoto and Rei's psychological decline, often hiding with Fuyumi as screams echoed. Natsuo shared a profound bond with Toya, becoming his confidant and emotional anchor amidst Toya's anguish over their father's rejection. Natsuo holds Enji directly accountable for Toya's presumed death at Sekoto Peak and Rei's hospitalization, fueling deep resentment. Physically, Natsuo is tall (181 cm / 5'11") and muscular, with spiky white hair featuring two strands over his forehead and gray eyes. Crimson streaks present in his childhood hair vanished by adulthood, possibly dyed or whitened naturally like Toya's. Born July 1st, he is 19 during his major debut. The Final War left him with burn scars on his face and body after intervening in Dabi and Endeavor's battle. Eight years later in the epilogue, these scars healed; he grew taller, developed a sharper jawline, and sports light stubble. Natsuo displays an easygoing nature that hardens intensely regarding family trauma. His profound, persistent resentment toward Enji drives him to openly condemn Enji's past abuse, neglect, and role in Toya's "death" and Rei's breakdown. He attends Fuyumi's orchestrated family gatherings solely for her sake, often storming out when Enji's presence overwhelms him. Despite his anger, he exhibits fierce loyalty and bravery. During the Final War, he joined Rei and Fuyumi confronting Dabi, using his Frost Quirk to help contain Dabi's self-destructive inferno—a crucial act enabling Shoto to subdue their brother. He cares deeply for his mother and siblings, regularly visiting hospitalized Rei and acknowledging Shoto's kindness, though struggling to mirror it. Natsuo's Frost Quirk generates ice for coating himself, though he lacks formal combat training. He utilized it in the Final War for protection against Dabi's flames and aiding containment efforts. As a medical welfare student, he aims to help others through this profession, reflecting his desire to transcend his traumatic past. This pursuit led him to leave the Todoroki household in adulthood, trusting Fuyumi with family matters while he focused on studies and a developing romantic relationship. Key events define his fraught interactions with Enji. Watching Endeavor battle Nomu Hood, Natsuo revealed conflicted emotions through horrified concern despite his hatred. His abduction by villain Ending forced a pivotal confrontation: Enji saved him without lethal force, prompting Natsuo to reject Endeavor's apology and admission of fault. He tearfully declared he could never forgive Enji like Shoto or Fuyumi might, yet acknowledged Enji's changed behavior and Fuyumi's resulting happiness. Dabi's public unmasking as Toya horrified Natsuo, compounding his trauma. Prioritizing stopping Toya's rampage over his grudge against Enji during the Final War, he temporarily sided with his father. Post-war, Natsuo maintains his stance toward Enji, shifting from outright hatred to detached acceptance. He informs Enji of plans to move away with his girlfriend and start a family, explicitly stating he desires no further relationship. Yet, he recognizes Enji has endured sufficient punishment, respects his ongoing atonement efforts, and offers parting words. His complete silence toward Toya contrasts this, implying lingering resentment for his brother's villainous actions, marking a shift toward closure without forgiveness.