Costume

A costume (コスチューム) is a distinguishing outfit worn by Heroes, Villains, and Vigilantes.

Heroes
Pro Heroes and Hero Course students alike often don specific battle wear to fight and strengthen their Quirks. Hero costumes are often equipped with gear to help Pro Heroes do their jobs more effectively, reducing risk to themselves while increasing their in-field efficiency. They also help the public recognize them and distinguish themselves from other heroes.

Costume designs can vary on a wide scale, including simple costumes, bodysuits, skinsuits, spacesuits, sets of armor and various other outfits depending on the Quirk functions and style preferences of the wearer. Support companies and genius scientists are the masterminds behind creating costumes for heroes.

Costumes are generally tailored specifically to the hero in order to amplify their abilities and weaken their drawbacks. Mirio Togata's costume was designed to help him use his Permeation Quirk without losing his clothes. His costume is lined with fibers created from his own hair so it will turn intangible along with him. This is just one specific way costumes help student heroes deal with their weaknesses.

For student heroes at U.A. High School, the costumes are developed at the school's expense. Costumes receive alterations throughout a student's career as they learn more about themselves and their Quirks. Minor alterations and support items are added by Power Loader in U.A.'s Development Studio, whereas bigger modifications require formal applications and are outsourced to a support company.

It is also possible for heroes to wear alternate costumes, such as winter costumes that are designed to keep them warm during colder months. These costumes can range from big changes, such as Katsuki Bakugo wearing a long, high collared black jacket so he can produce his nitroglycerin-like sweat as efficiently, to more simple additions such as Momo Yaoyorozu adding a winter cloak to her costume, which is designed to be revealing so she can create larger objects with ease. Additionally, there can also be costumes made especially for certain missions, such as the stealth costumes worn by Izuku Midoriya, Katsuki, and Shoto Todoroki during their mission against Humarise.

Hero costumes do not necessarily need to be sourced from support companies, at least not for heroes in training. Izuku was allowed to wear a homemade costume that was sewn by his mother in a practical battle session, although he later had it upgraded to a proper hero costume after it was destroyed. During his younger years while in America, All Might wore regular clothing while performing hero duties, although the damage they sustained would later have him don his iconic costumes that were capable of sustaining major damage.

Costumes can also include battle prosthetics that are meant to help heroes with physical disabilities. The most prominent example of this is Ectoplasm, who wears replacement legs that are designed for combat.

Villains
While heroes are welcome to proudly don their costumes, villains do not have access to support items, via legal channels. Villains generally use costumes as a way to hide their identity, rather than distinguish themselves like Pro Heroes. There are exceptions though, Spinner wears his costume as a homage to his idol, the Hero Killer: Stain, meaning that villains can wear costumes that represent a message they wish to spread.

Support items and villain costumes are sold through the black market, using brokers like Giran. He provided the Vanguard Action Squad with the proper gear to help support their Quirks. Himiko Toga received the most dramatic change in costume; her equipment functions to help her gather blood for her Transform Quirk.

Although villains don't usually rely on industrial support, there are exceptions, such as the Grand Commander of the Meta Liberation Army, Re-Destro, also being the President and CEO of Detnerat and thus having access to the company's support gear, along with his fellow MLA executives. When in need of more power, Re-Destro wears a robotic set of armor dubbed Claustro, that purposefully binds into him as to amplify his Meta Ability, Stress, which allows him to turn stress, anger, and frustration into raw power.

Like with heroes, villain channels can also deal in prosthetic limbs; Mr. Compress was given a prosthetic arm by Detnerat that allows him to shoot his marbles through his fingers. Another example is Re-Destro, who was fit with mechanical legs, although they don't support his Meta Ability that well.

It is also common for villains to rely on Quirk-enhancing drugs, like Trigger.

Vigilantes
Vigilantes primarily wear costumes to conceal their true identities, given that they fight villains without any proper authority or licensing, thus making what they do illegal. Examples of this include the Naruhata Vigilantes, who wear their costumes to hide who they really are.

Unlike Pro Heroes, vigilantes don't have access to official support companies, and instead make use out of whatever they have, such as The Crawler donning an All Might hoodie and a face mask. Other vigilantes however are willing to resort to the black market to acquire support equipment and weaponry, such as Knuckleduster.

Known Costume Developers

 * Mei Hatsume: U.A.'s Support Department student. An energetic inventor who has come up with countless ideas for hero support items.
 * Power Loader: U.A.'s teacher and head of U.A.'s Development Studio. Responsible for overseeing and developing minor alterations in costumes for U.A.'s hero students.
 * Giran: A villain and broker in Japan's underworld who sells black market costumes and support gear to villains, with his primary clients being the League of Villains. He also deals with vigilantes, like Knuckleduster.
 * David Shield: One of the most well-known costume designers in the world. He designed all four of All Might's costumes during his run as the No. 1 Hero. It's the support of these costumes that allows All Might to fight at full power without risking damage to himself or his clothing.
 * Melissa Shield: A Quirkless young woman, who envisions to be an inventor like her dad, David Shield. She created the hero costume Endeavor wears as the No. 1 Hero.
 * Detnerat: A company that specializes in developing clothing and support items for civilians with abnormal bodies or anatomy. Recently entered the hero costume market. It has ties with the black market, providing villains with equipment that collects their battle data and self-destructs to avoid being traced back to them. They have also plagiarized most of their work from creations in America.

Trivia

 * Following the debut of the R-Rated Hero: Midnight, the government passed a law limiting the amount of skin that could be exposed on a hero costume, due to Midnight wearing an inappropriately revealing costume.
 * Many in Class 1-A share costume designers:
 * Tsuyu Asui, Momo, Minoru Mineta, and Mina Ashido all share the same costume designer.
 * Ochaco Uraraka and Katsuki share the same costume designer.
 * Kyoka Jiro and Denki Kaminari share the same costume designer.
 * Izuku's later costumes share the same designer as Shoto's.
 * Hanta Sero and Eijiro Kirishima share the same costume designer.
 * The following students currently have no listed connections between costume designers amongst each other: Yuga Aoyama, Toru Hagakure, Tenya, Rikido Sato, Mezo Shoji, Koji Koda, and Fumikage Tokoyami.
 * Some costume developers are revealed to have personal trademarks, as seen with Katsuki and Ochaco's costumes both including two black dots.
 * Melissa Shield, daughter of David Shield who created All Might's costumes, helped to create the remodelled hero costume for Endeavor after he became the No. 1 Hero.