Izuku Midoriya was born without a Quirk in a superhuman society, enduring extensive childhood bullying, particularly from Katsuki Bakugo who mockingly nicknamed him "Deku" to imply worthlessness. Despite this, he clung to his lifelong dream of becoming a hero, deeply inspired by the symbol of peace, All Might. A pivotal encounter occurred when Izuku demonstrated extraordinary bravery by rushing to save Bakugo from a villain, despite being powerless. This act impressed All Might, who revealed his weakened form and offered Izuku his transferable Quirk, One For All, recognizing the boy's innate heroism. After ten months of rigorous physical training, Izuku inherited One For All by consuming a strand of All Might's hair, enabling his admission to U.A. High School's Class 1-A. Initially, he struggled to control One For All, often sustaining severe injuries like broken bones. His early hero costume, designed by his mother, featured a green jumpsuit and mask resembling All Might. It underwent multiple revisions: "Costume Gamma" accommodated his kick-based "Shoot Style," "Costume Epsilon" added Mid-Gauntlets and Gran Torino's cape for post-war stealth, and "Costume Zeta" featured darker colors and gold highlights reflecting his maturity. After the Final War, his "Costume Origin" emerged, succeeded by a technologically advanced suit in adulthood. Izuku's personality combines intense compassion, relentless optimism, and profound responsibility. His Quirkless upbringing fostered deep empathy, driving him to save even villains like Lady Nagant or Tomura Shigaraki, believing their circumstances could be redeemed. He frequently prioritized others' safety over his well-being, exemplified when he left U.A. during the Paranormal Liberation War to protect classmates from All For One and Shigaraki targeting One For All. This isolation led to temporary coldness and paranoia, though his classmates intervened to restore his trust in collective support. His courage manifested in high-stakes battles, like rescuing Eri from Overhaul or confronting Muscular. Key relationships shaped his journey. All Might served as mentor and father figure; their bond evolved into a familial dynamic where All Might openly expressed pride and affection, while Izuku sought to protect him. Ochaco Uraraka helped him reclaim "Deku" as a symbol of perseverance, with mutual romantic feelings developing. His dynamic with Bakugo shifted from antagonism to grudging respect and eventual reconciliation, culminating in Bakugo's apology. Izuku also profoundly influenced peers like Shoto Todoroki, aiding him in overcoming trauma. Throughout his development, Izuku mastered multiple Quirks within One For All, including Blackwhip and Float, while refining combat strategies. His physical appearance changed significantly, marked by battle scars and a more muscular build. After the Final War, he defeated Shigaraki and All For One but lost One For All permanently, rendering him Quirkless again. Post-graduation, he became a history teacher at U.A., later returning to hero work using advanced support technology. By age 26, he achieved the rank of No. 4 Pro Hero, balancing teaching duties with active heroism.