Yui Kodai

Yui Kodai is a student in Class 1-B at U.A. High School.

Appearance
Yui has dark, shoulder-length, bob-shaped hair. She also has fair skin and an athletic build, with dark blue eyes and a neutral expression usually on her face.

Her Hero Costume consists of a simple cap on her head and a dark body suit with light patches on her chest, arms and legs, she wears elbow length gloves and a belt with a pouch on one side and a short skirt. She also has straps over her shoulders with pouches on either of them.

Personality
Yui is a quiet girl that rarely expresses any emotions. Some of her classmates consider her a Kuudere.

Sports Festival Arc
In the Prelimaries Race, she made it to 31st place. Before the Cavalry Battle, she formed Team Kodai with Kojiro Bondo and Manga Fukidashi. As her team goes towards Team Bakugo, Bondo used his quirk to interfere against Team Bakugo. Then after Bakugo takes most of Team Monoma's headbands, her team goes after Team Monoma, but her team goes away from Team Monoma, ending with zero points. Her team fails to advance to the tournament.

School Trip Arc
On the day of the forest lodge trip, when Neito mocks Class 1-A, Yui is seen observing.

When Class 1-B arrives at the training camp, their homeroom teacher Vlad King explains that they will be extending their Quirks and that the more they use their Quirks, the stronger they will be by breaking their limits. When Class 1-B witnesses Class 1-A's training, Itsuka asks Shota how they can observe everyone, and he explains that is the reason the Pussycats are around. Later that night, Class 1-B act as the scaring group during the test of courage. In the forest, Itsuka and Juzo commends Yui for scaring Shoto and Katsuki. However, smoke entering the forest knocks out Juzo. Itsuka takes action and uses her Quirk to cover Yui from the smoke. Yui and the other 1-B students are later rescued by Shota during the aftermath of the Vanguard Action Squad Invasion.

Joint Training Arc
All of Class 1-B shows up for a Joint Training exercise, with Neito loudly claiming that the momentum is now moving to their side. Upon selecting teams, Yui is paired up with Neito, Reiko, Nirengeki, and Hitoshi for the final match.

Quirk and Abilities
Size (サイズ): Yui can make herself shrink to at least half of Bondo's size. She can also make herself larger, as seen when she tries to scare off Shoto and Katsuki.

Itsuka Kendou
Itsuka protects Yui from the poisonous smoke during the Test of Courage, and also, Itsuka addresses Yui by her given name, implying Yui and Itsuka are pretty close.

Trivia

 * Her name contains the kanji for "small" (小), "big" (大) and "only" (唯).
 * Yui's design appears to be based off one of Ochaco's prototype concepts, as seen on the bottom right corner.
 * Yui likes Matryoshka dolls.