In the film My Hero Academia: World Heroes Mission, Izuku Midoriya, known by his hero name Deku, finds himself thrust into a global crisis that forces him to operate far outside the bounds of a conventional hero. At this stage in his journey, he is a second-year student at U.A. High School and is already well into his work study under the Number One Pro Hero, Endeavor. The movie places him in the fictional republic of Otheon, where he is tasked with helping to dismantle a doomsday terrorist organization called Humarise. This group, driven by the Quirk Doomsday Theory, believes that superhuman abilities, known as Quirks, will eventually lead to humanity's self-destruction. Their plan is to activate lethal Trigger Bombs worldwide, devices that can cause Quirk users to go berserk and die, in order to create a new world order for the Quirkless.

As a character, Izuku remains defined by his signature traits: an analytical mind, an unyielding sense of empathy, and a self-sacrificing drive to save others. Early in the film, he is framed for a brutal murder he did not commit, a crime orchestrated by corrupt officials in league with Humarise. This accusation forces him to become a fugitive. While other heroes work openly to disarm the bombs, Izuku must operate in the shadows, evading both the terrorist group and the local authorities who believe him to be a criminal. Rather than focusing on clearing his own name, his immediate instinct is to protect the people caught in the crossfire and stop the larger threat, a decision that speaks directly to his core heroic ideology.

His costume in this mission reflects his fugitive status and the international scope of the operation. He dons a black stealth suit with teal-green accents, reinforced gear provided by the World Heroes Association, and his signature red boots. This sleeker design is practical for infiltration and escape, a departure from his usual bright green attire. His physical appearance remains consistent with his established design: green, untidy hair, large green eyes, and freckled cheeks. However, his body shows the accumulating toll of his battles, having grown more muscular and scarred, visual markers of his intense training and the dangerous confrontations he has endured.

The film places significant emphasis on his relationships, particularly the one he forms with Rody Soul, a cynical local pickpocket who becomes his unwilling partner on the run. Izuku stumbles upon Rody during a stakeout, mistakenly believing the courier is connected to a Humarise asset. After the framing, the two are forced to flee together, and their dynamic forms the emotional core of the story. Where Izuku is optimistic and dutiful, Rody is pragmatic, weary, and initially resentful of heroes. Throughout their journey on a decrepit train and through the industrial underbelly of Otheon, Izuku’s genuine nature breaks through Rody’s hardened exterior. His empathy does not waver even when he discovers the truth about Rody's family or his companion's own fears, showcasing his ability to inspire courage and hope even in someone who has lost faith in the system.

His role in the plot evolves from a simple operative to the world's last hope. Because the authorities are hunting him, the mission to input the disarm code and stop the global bombs ultimately falls to him and Rody. This isolation highlights his self-reliance and his ability to adapt. Despite being a student, he demonstrates leadership and tactical prowess far beyond his years, formulating plans on the fly while protecting a civilian with no combat training.

In terms of development, World Heroes Mission showcases Izuku’s growing mastery over One For All, the transferable Quirk he inherited from All Might. By this point in the timeline, he has awakened and begun to control the previous users' Quirks that lie dormant within One For All. Notably, he utilizes Blackwhip, the ability to generate tendrils of dark energy for capture, traversal, and attack, with impressive precision. He is no longer the novice who breaks his bones with every punch; he can access higher percentages of One For All's full power without shattering his limbs, allowing for fluid and devastating combat sequences. The film culminates in a confrontation with Humarise's leader, Flect Turn, whose Reflection Quirk makes him nearly invincible by repelling any attack back at the assailant with equal force. Flect Turn is a thematic foil, a man who despises his own Quirk as a curse, contrasting sharply with Izuku, who was born Quirkless yet views his power as a gift to help others.

His most notable abilities are pushed to their absolute limit in this final battle. Realizing that a standard attack will only rebound and destroy him, Izuku devises a strategy to overwhelm Flect Turn's reflective barrier. He pushes One For All to its maximum output, not in a single burst, but in a sustained, overwhelming torrent of power. By activating a state resembling Full Cowling at one hundred percent, he essentially unleashes a storm of force that exceeds the reflective limit of Flect Turn's Quirk, shattering his defense with raw, unrelenting willpower. This victory is not just a physical triumph but an ideological one, proving that relentless effort and the drive to save others can overcome a fatalistic nihilism. Throughout the mission, Izuku embodies the message of never giving up and taking full responsibility, inspiring Rody to make the crucial play that saves the world. In the end, Izuku remains the Symbol of Hope, a hero who believes that everyone is worth saving, regardless of the cost to himself.