WARNING: The following contains spoilers for the My Hero Academia manga available to read on Viz Media.
One of the most recognizable aspects of any pro hero in My Hero Academia is their signature costume. As heroes-in-training, the students of U.A. High School gradually improve their Quirks and combat abilities -- and as they mature both physically and mentally, their costumes change alongside them to accommodate their growth. It's not uncommon to go through many drafts before a hero ends up with a final look that complements them in every way.
The series' protagonist Izuku "Deku" Midoriya is a great example of this. While he has yet to graduate and become a pro, his costume has undergone some major changes over the course of the story, and every design marks a significant point in his hero journey. Let's take a look at each of them.
Deku's first costume is by far the most comical, but is nostalgic of Western comic book heroes from the 20th century. It consists of a full-body green jumpsuit, simple elbow and knee pads, a red belt and his distinguishable red shoes. The most notable elements are the mask with long ears, meant to resemble All Might's hair, and the respirator, which vaguely resembles All Might's smile.
This design debuted in Season 1 and while it didn't last longer than two episodes, it's still incredibly important as signifying Deku's starting point. While it isn't the most practical in terms of supporting or strengthening his Quirk and abilities, it serves as an homage to All Might, his mentor, and Deku's determination in becoming a hero. It's also a tribute to his mother, who bought him the jumpsuit as a sign of her unwavering support.
We catch our first glimpse of Deku's second hero costume upon meeting Gran Torino in Season 2's Hero Killer arc. This design is better suited for combat and features sturdier support equipment, while also extending his knee pads up to his thighs and changing his respirator to diamond-shaped metal material. His mask with the long ears is still part of his costume, but Deku doesn't wear it.
Shortly after attaining Costume Beta, Deku attains more control over One For All and its drawbacks. He creates Full Cowl, which becomes a core aspect of his fighting style, improving his strength, mobility and overall abilities. Although these changes were made by the support department without Deku's knowledge, it holds remnants of his mother's suit and is his first step in making One For All his own.
Before the Provisional License Exam, Deku and his classmates are tasked with creating ultimate moves, which forces Deku to think of more creative ways to utilize One For All. He soon realizes that his fighting style focuses on his arms -- subconsciously done to mimic All Might -- but as a result, his arms have taken significant damage. To lessen this burden, Deku develops Shoot Style, which focuses on his legs for offensive attacks.
To accommodate for Shoot Style, Costume Gamma adds iron soles to his shoes to magnify the power in his kicks and arm braces, thereby lessening the strain on his arms. Later, Air Force Gloves are included to give Deku's finger flicks a more concentrated blast so powerful that they're referred to as air guns. This third design properly diverges Deku from All Might and makes major strides in creating his own hero identity.
The third film in the MHA franchise, World Heroes' Mission, gives Deku, Katsuki Bakugo and Shoto Todoroki new costumes in the form of stealth suits. Based on Costume Gamma, this new look has a sleeker design and is almost completely black aside from its epic green accents. The biggest modification turns Deku's mask into a hood clearly meant for stealth missions.
While the movie doesn't hit theatres until the end of the month, trailers and a special chapter acting as a prequel to the film -- My Hero Academia Special Spin-Off: Endeavor's Mission -- point out that the trio will be accompanying Endeavor on an international mission to stop an evil organization hellbent on worldwide chaos. Focusing on stealth rather than outright combat is new territory for Deku and will certainly widen his skillset.
The most recent change to Deku's costume is much darker and represents his shift from hero student to vigilante. Again, Deku's costume changes to adapt with him and his usage of One For All. However, it seems that this darker version of his hero outfit has been directly influenced by his deteriorating state of mind since the war against the Paranormal Liberation Front.
This new suit is an edgier and more battered version that's hauntingly reminiscent of Costume Alpha. Deku wears both his mask and respirator, yet the costume is far from being as comical as it used to be. It also features mid-gauntlets that support his body, allowing him to exceed his limit of using 45% of One For All. Finally, Deku sports Gran Torino's scarred yellow cape. Stronger than ever, Deku aims to protect and capture all the escaped villains while keeping his identity a secret. This menacing new look represents the burden Deku carries as a successor of One For All and the lasting effect it has on him.