Mei takes to the field with her classmates from the Department of Support. After the opening ceremony, Mei competes in the Obstacle Race.
When Ochaco Uraraka and Mina Ashido reach The Fall section of the course, Mei makes herself and all of her gadgets known. Mina questions why Mei is allowed to wear special gear, to which Mei replies she developed them herself and it allows for a more fair competition at the Festival because Hero Course students receive training. Mei uses her Wire Arrow and Hover Soles to cross tightrope-laced abyss with ease, laughing gleefully as she does it. She eventually finishes the race and places forty-first, qualifying her to compete in the Cavalry Battle.
While choosing teams for the Cavalry Battle, Mei spots Izuku Midoriya, the first place contestant, and confronts him. She pitches to join his team because all eyes are on him and if she joins him, then all eyes will be on her and her "babies" as well. Izuku is startled by Mei's assertive personality, but he is won over after she shows off several of her gadgets. Izuku even recognizes one from the Pro-Hero Air Jet, and the two have a friendly discussion about it.
Once the Cavalry Battle begins, Izuku is forced to use the Jet Pack to escape pursuing teams. Mei asks how her gadgets perform and is joyous when Izuku replies her "babies" are amazing. After getting trapped by one of Minoru Mineta's spheres, Izuku is forced to break one of the hover soles, much to Mei's dismay. After finally getting away, Mei and her team are confronted by Team Todoroki.
Denki Kaminari attacks using his electricity, which short-circuits Team Midoriya's jetpack. When it fails to work and Team Midoriya are unable to flee from Team Todoroki, Mei comments that her baby needs some upgrades. Thanks to Izuku's strategy, Team Midoriya are able to evade Team Todoroki for the back half of the round. However, their luck runs out when Tenyas Iida uses his special Recipro Burst technique to steal Mei's team's points in an instant. Mei agrees with Fumikage Tokoyami that they should try for other points, but Izuku refuses and they engage Team Todoroki again.
Izuku is able to steal one of their headbands, but Mei notices it is the wrong one. They try one more time to recover their points but run out of time as the Cavalry Battle ends. When Izuku tries to apologize for losing, Mei and Ochaco point him towards Fumikage, who reveals he was able to steal a headband worth enough points to advance. Team Midoriya takes fourth place, and Mei qualifies for the finals.
After a short break following the completion of the second round event, it is announced the sixteen qualifiying students will duel in a one on one fighting tournament. Once the matchups are announced, she approaches "legs" to ask him if he's Tenya Iida, to which he confirms.
Mei offers Tenya Iida some of her equipment and tells him it is to keep the fight fair between them. Moved by her sportsmanship, Tenya agrees. However, when their fight begins Mei manipulates Tenya into showing off her gear while evading his pursuit. She uses her Quirk to keep an eye on the support company representatives as she transforms the battle into a commercial for her support items.
For the next ten minutes, Mei continues her fight while explaining the features of her items to the audience using a mic attached to her headgear. Satisfied with her exposure, Mei steps out of bounds and eliminates herself from the tournament, allowing Tenya to advance to the next round. Mei thanks Tenya for allowing her to use him and apologizes for it, much to Tenya's annoyance.
Mei appears again as Izuku, Ochaco and Tenya visits the workshop to improve his hero costume. An explosion catapults her through the door and lands on Izuku as he tries to enter. She recalls Izuku only to turn away and tell him that she's busy in the workshop. However, upon hearing that Izuku wants to upgrade, she turns all her attention to him. While Power Loader and Izuku discuss how they can upgrade his costume, Mei grabs onto Izuku to feel his muscles. Mei equips Izuku with her 49th invention, a Power Suit. However, the armor moves independent from Izuku and hurts him, causing her to apologize for programming the range of motion incorrectly.
Upon hearing Tenya's request for a gadget that lets him cool his legs, Mei equips him with her 36th gadget, an arm brace with rocket motors, which promptly sends Tenya into the ceiling. When Tenya complains, since his quirk is located in his legs, she reasoned that he could run with his arms, to cool his legs. It is this suggestion that leads Izuku to develop his new set of moves, Shoot Style, which utilize his legs more than his arms. Power Loader scolds Mei for her carelessness and she returns to her work, though he remarks that Mei is an outstanding student with a remarkable ability to invent. Shortly after, Mei tries to improve Ochaco's costume with some gadgets, much to Ochaco's dismay. In the end, Izuku settled for an arm brace that reduces the strain on his arm and boots with a coil-mechanism, that absorb some of the impact force of his kicks.
Later, Eijiro Kirishima and Denki Kaminari go to the workshop to ask Mei and Power Loader to improve their costumes. Denki in particular explains that he is unable to control the flow of his electricity by himself, so he asks them to design a device that allows him to control it. Mei and Power Loader accept his request and manufacturer for him the Sharpshooting Gear.
Mei is excited by the U.A. School Festival because it represents for the students who do not belong to the Hero Department the opportunity to shine. Mei decides to build her "Baby number 202", a large combat suit, with which she plans to attract the attention of tons of companies. She is so dedicated to this project that she does not even bother to bathe and she plans to clean up once her project is finished. She does not sleep much either.
During the weeks of preparation Izuku, along with Mirio and Eri, goes and sees U.A.'s Development Studio. Mei asks Izuku about his Hero equipment and to inform her if he needs anything. At some point, Izuku asks mei to make him a pair of gloves that allows him to compensate for the strength of his hands.
Days later, Mei was out in the forest, following one of her latest gadgets and comes across Izuku and All Might who caught her device. All Might (while disguising his voice) catches her device and hands it back to her, as she states it was just acting up. Mei then notices Izuku and tells him the item that he requested is similar to one of her inventions and is customizing it for his use, to which he thanks her. Mei leaves while following after her device.
Shortly before the festival begins, Mei finally cleans and kempt herself. She presents her robot suit to several company representatives and, when the festival ends, she finally goes to sleep.