Episode 1

Izuku Midoriya: Origin is the first episode of the Boku no Hero Academia anime.

Summary
A young Izuku Midoriya stands up to Katsuki Bakugou, in order to defend another child from being bullied. Katsuki mocks him for being Quirkless and attempting to play hero.

Back to present time, a now 14-year-old Izuku watches Heroes battle an enormous villain. A brief prologue is then shown: one day in Quig Quig, China, a luminiscent baby was born with a unique power. Then, as time passed, the similar phenomena happened all over the world, and soon the majority of the population had obtained superhuman powers -- known as "Quirks". Due to that, people were able to pursue heroism as a profession.

Kamui Wood is shown battling the villain while a crowd watches. Izuku approaches them, wondering who is fighting. Kamui states that the villain used his Quirk for illegal purposes, and uses Lacquered Chains Prison on him in an attempt to stop his movement.

However, Mount Lady shows up, using Canyon Cannon on the enemy to defeat him. Several people start photographing the heroine as she declares that today is her debut and asks for the rest to be left up to her. Izuku starts rapidly taking notes about Mount Lagy's Quirk, Gigantification, and a man wonders if he's aiming to be a hero, wishing him good luck, to which Izuku happily answers that he'll do his best. At Izuku's middle school, a teacher scolds the class, telling them it's time they think about their futures. He says he will hand out the printouts on the students' desired life-course, but knows they all want to be heroes. As the class starts using their Quirks, he reminds them they're not allowed to use them during school hours.

Katsuki tells the teacher not to group him with everyone else, because his Quirk is stronger. His classmates yell at him for that, but Katsuki tells them to shut up, and they remember he's aiming for Yuuei High. As the students comment about the difficulty of the exam, Katsuki declares he aced the mock exam and intends to surpass even All Might as the top hero, but is interrupted by the teacher mentioning that Izuku also wanted to go to Yuuei. The whole class then turns to face Izuku, erupting in laughter moments later.

Izuku's classmates say there's no way he will be able to get into the hero course if all he can do is study. Izuku attempts to defend himself, but Katsuki aims an explosion at him, saying that Izuku shouldn't put himself in the same level as him, since he doesn't have a Quirk. Izuku explains that he is not trying to compete with Katsuki, and is only trying to follow the dream he had since childhood, because he won't know if he can accomplish it if he doesn't try. Katsuki says that the exam is impossible for him, as the whole class looks down on Izuku, snickering.

Elsewhere, a villain with a fluid, slime-like body is on the loose. As a crowd nearby watches him run away, a person comments that there is no end to villains. A man then answers that there indeed is and end to them, because he is there. Back at Izuku's middle school, he picks up his notebook while reading about and incident in his phone, but as he gets ready to get home and take notes, Katsuki approaches, exploding the notebook with his Quirk. He then throws it out the window, and tells Izuku, who doesn't reply to his taunts, to give up on Yuuei and dive off the rooftop. As Izuku picks up his notebook, he remembers an incident from his childhood: watching a video of All Might making his debut as a hero, saving over 100 people. Izuku says he wants to be just like him, but is later told by a doctor to give up: he has two joints in his pinky toe, which shows that he is Quirkless. Later that day, Izuku watches the video again, crying, and asks his mother if he can still be a hero like All Might, to which she teary apologizes.

Back to present time, Izuku is attacked by the runaway slime-like villain shown before while walking home. He fears for his life. Suddenly, All Might appears and uses Texas Smash against the villain, a powerful wind pressure move that defeats the villain. Izuku vaguely sees All Might and faints shortly thereafter. Once Izuku wakes up, he's shocked to see his idol right in front of him. He asks for his autograph, but sees it's already on his notebook. After seeing Izuku is safe, All Might starts leaving with the villain in his custody, but Izuku grabs onto his leg and ends up flying with him. When All Might realizes it, he tells Izuku to let go of him, but Izuku says he'd die if he did, so All Might looks for a place to land on. All Might starts bleeding from his mouth, and gets worried due to it.

All Might lands on the rooftop of a building. Izuku asks the man if someone who doesn't have a Quirk could also be a hero like him.

Manga & Anime Differences

 * In the manga, the Luminescent Baby baby born was being held by a doctor, while in anime the baby is in its crib.
 * The anime adds a scene where the giant villain breaks an energy pole and Desutegoro catches it, preventing it from hurting the civilians. His hero alias is also revealed to be "Punching Hero".
 * Backdraft also gets a short extra scene, where he creates a fence out of water to prevent people from getting close to danger. He's referred to as a "rescue specialist".
 * In the anime, before attacking Izuku, the slime-like villain is seen running past a market, where All Might, in his civilian form, spots him and turns into his hero form unnoticed, and then proclaims there's no need to worry as he's there.
 * In the anime, before asking All Might if even Quirkless people can become Heroes, Izuku remembers what several people have said to him regarding the matter, including the Doctor, his own mother, and Katsuki.