Izuku Midoriya, known as Deku, was born Quirkless in a superhuman society, enduring childhood bullying and discrimination. Katsuki Bakugo mockingly bestowed the nickname "Deku," meaning "useless." Despite this, Midoriya clung to his dream of becoming a hero, inspired by All Might. His inherent heroism emerged when he risked his life to save Bakugo from a villain, an act that impressed All Might. Consequently, All Might chose Midoriya as the successor to the transferable Quirk One For All. Following intensive training, Midoriya inherited this power, becoming its ninth wielder. Enrolling at U.A. High School, Midoriya initially struggled to control One For All's overwhelming power, frequently injuring himself due to the Quirk's intensity and his own self-sacrificial nature. To mitigate damage to his arms, he developed "Shoot Style," focusing on kicks, and received multiple costume upgrades to support this fighting style. Over time, he unlocked additional Quirks stored within One For All, including Blackwhip, granting him energy tendrils. His leadership and analytical skills earned classmates' trust, though he often internalized pressure, believing he alone should confront threats like All For One and Tomura Shigaraki. During the Paranormal Liberation War, Midoriya's status as One For All's successor made him a target. To protect classmates, he left U.A., adopting a solitary vigilante approach. His "Costume Epsilon" from this period featured a mask and tattered cape, reflecting his darker, isolated state. Friends eventually persuaded him to return, and he led the final battle against Shigaraki and All For One. He achieved victory but permanently lost One For All, reverting to Quirklessness. In *World Heroes' Mission*, Midoriya joined a global operation against the terrorist group Humarise. Stationed in Otheon with Katsuki Bakugo and Shoto Todoroki, he was framed for murder after intervening in a robbery and encountering courier Rody Soul. Fleeing with Rody, Midoriya uncovered Humarise's plot to deploy "Trigger Bombs" designed to kill Quirk users. Partnering with Rody, he deciphered clues left by Rody's father—a former Humarise scientist—to locate the bombs' deactivation device. In the final battle, he faced Humarise leader Flect Turn, whose reflection Quirk countered physical attacks. Midoriya overcame this by unleashing One For All at 100% intensity, overwhelming Flect's defenses while Rody activated the deactivation device. After losing his Quirk, Midoriya became a history teacher at U.A. Eight years later, technological advancements enabled his return to hero work as the No. 4 Pro Hero, utilizing a nano-tech-based costume. His character arc consistently emphasizes self-sacrifice, empathy, and the belief that heroes should save even those deemed irredeemable.