My Hero Academia represents an ever-growing superhero universe, and now each part is drawing a little closer together as anime-only characters get a chance to shine in manga form. My Hero Academia: Team Up Missions is a spinoff where various characters are paired up, often in unlikely combinations, and given the chance to learn and function together. Aside from other UA students, class 1-A students also get sent out to work alongside pro heroes like Hawks, students from other schools like Shiketsu High and Ketsubutsu Academy, and in at least one case, a very special guest from overseas.
In the first volume of My Hero Academia: Team Up Missions, the original character from the first film My Hero Academia: Two Heroes, Melissa Shield, appears alongside her father Dave. In the film, it is revealed that Dave had helped design All Might's costumes and equipment when he visited America, and Melissa herself develops a gauntlet that allows Deku to fight alongside All Might at full strength, if only briefly. However, despite their seemingly important connection to All Might, the father/daughter pair had not previously appeared in the manga at all. A one-shot included in this volume was created to promote the film, offering a look at her life as a quirkless girl and how she can contribute to help heroes, even without powers. She winds up creating support items and equipment, like her father, which naturally led fans to draw comparisons to Midoriya's usual inventor friend, Mei Hatsume.
Team Up Missions takes this idea and runs with it, bringing her over for a brief visit to UA, where Melissa and Hatsume are given the chance to meet. While they quickly begin swapping stories and ideas, the friendliness soon builds into a bit of a rivalry as it's revealed that each of them has a very different approach to creating and inventing. Hatsume represents the artistic approach—when she's struck with inspiration, she can create incredible things with great speed, but she's not very concerned with the end user's desires. Melissa prefers to take a hero's requests into consideration, but her ideas rely on cutting edge technology that doesn't always function right, and they go through so many revisions that they tend to take too long to be developed into working order.
While it's not the usual kind of confrontation seen between My Hero Academia characters, pitting the two support girls against each other makes for an entertaining bit, and officially brings Melissa over to the comics side of the franchise. The main series comic has alluded to her before, but never mentioned her by name or had her show up; most recently, Endeavor's new costume was said to be "developed by a girl from the States." Given that this chapter opens with Melissa at Endeavor's agency, this would seem to confirm that she's the girl in question.
My Hero Academia: Team Up Missions is in a weird spot as far as My Hero Academia canon goes, given that there's not really a span of time where these kind of side missions could logically fit in. But at the very least, the comic offers some amusing pairings and gives smaller characters like these two a little extra time in the spotlight. And although Melissa Shield returns home to America, the stage is certainly set for a return appearance, should the writers so desire.