Born Quirkless to Inko Midoriya and overseas-based father Hisashi Midoriya, Izuku Midoriya grew up primarily in Shizuoka Prefecture under his mother's care. From age four, he endured bullying from childhood acquaintance Katsuki Bakugo, who mocked his lack of superhuman abilities and branded him with the derogatory nickname "Deku," symbolizing uselessness. Despite societal discouragement, Izuku fiercely clung to his dream of becoming a hero, inspired by the Symbol of Peace, All Might. He honed sharp analytical skills by meticulously documenting hero Quirks and strategies in detailed notebooks. A turning point arrived when Izuku risked his life, Quirkless, to save Bakugo from a Sludge Villain. This act of courage deeply impressed All Might, who revealed his weakened true form as Toshinori Yagi. After testing Izuku's resolve, All Might offered him his power, One For All—a stockpiling Quirk passed through generations. Izuku underwent ten grueling months of physical training to inherit it, culminating in consuming a strand of All Might's hair. This achievement secured his enrollment at U.A. High School, the prestigious hero academy. At U.A., Izuku reclaimed the name "Deku" as his hero identity after classmate Ochaco Uraraka reframed it as an abbreviation of "dekiru" ("you can do it"). His initial costume, designed by his mother, featured a green jumpsuit with bunny-eared hood and a mask echoing All Might's smile. This costume evolved through multiple iterations (up to "Costume Zeta"), integrating support gear: Iron Soles for kicking, Air Force Gloves for ranged attacks, and Melissa Shield's Mid-Gauntlets to safely channel higher percentages of One For All. The final design incorporated dark green coloring, gold accents, a respirator, and Gran Torino's cape repurposed as a scarf. Initially, One For All caused self-destructive injuries due to Izuku's inability to control its full power. He developed the "Full Cowling" technique to distribute power across his body, mitigating damage. Later, he progressively unlocked six additional Quirks from past users during high-stress situations like the joint training arc or battles against villains such as Overhaul: Black Whip (tendrils for capture/mobility), Float (flight), Fa Jin (kinetic energy stockpiling), Gearshift (velocity manipulation), Danger Sense (precognitive threat detection), and Smokescreen (obscuring smoke). Izuku's personality transformed from a timid, self-doubting boy into a resolute yet self-sacrificing hero. His defining trait remained extreme selflessness—repeatedly risking his life to save others—alongside a habit of strategic muttering during analysis. He extended empathy even to villains, seeking to understand their origins and offering redemption, as seen with Gentle Criminal and Lady Nagant. His confrontation with Overhaul crystallized his resolve to protect the abused child Eri, declaring, "If I can’t save one little girl right in front of me... how can I be a hero who saves everyone?" Learning that Tomura Shigaraki, All Might's archvillain successor, could steal One For All, Izuku left U.A. to protect classmates, informing them of the Quirk's legacy via letters. During this isolated "Dark Hero" phase, he fought villains alone, growing increasingly paranoid until Class 1-A intervened. Their reunion, including Bakugo's apology for past bullying, restored his faith in collective heroism. His relationship with All Might deepened from idolization to profound mentorship, with All Might guiding him through One For All's legacy. His rivalry with Bakugo shifted from hostility to fierce mutual respect, culminating in Bakugo acknowledging Izuku's strength. Romantic feelings developed between Izuku and Ochaco, though neither openly confessed. Across official media, including films like *Two Heroes* and *World Heroes' Mission*, Izuku collaborated with international heroes against global threats like the Quirk-erasing drug Trigger. Post-graduation, he became a professional hero and later a teacher at U.A., continuing All Might's legacy while forging his own path. Physically, his initial skinniness yielded to a muscular build through training, while excessive Quirk usage scarred his arms. A significant burn scar from Dabi marked his torso. His worldview matured, recognizing societal complexity: "Nothing is truly black-and-white... That’s why I must keep reaching my hand out to help!"