All the chaos!

"Huh, I just got a text from the Support Course's representative," Izuku noted as he checked his phone. It was the next day, and they were currently in the study hall of the school. They had all agreed that one of their homes would be used during the weekday session, and that study hall would be used on the weekend one. Less students to disturb were around on study halls during the weekend.

"Huh, really?" Momo asked, looking over his shoulder. Izuku proceeded to read aloud that one member of the class was going to join to get her grades up and sustain privileges to use the Support Course Studio.

"...P.S... she's your problem now..." Izuku said as more students proceeded to file in. "... what's that supposed to mean?" he wondered.

"...sounds like she's a real troublemaker," Jiro remarked. Her assumption proved prophetic as Mei arrived, carrying a duffel bag full of things for her to tinker with while they studied. Momo immediately liked her, and was already making plans to bring her into the harem.

At first, things seemed to go alright, with Mei studying quietly with them... This lasted for all of five minutes. Then she decided she needed a break, and took a toaster with four long metal legs out of the bag and started to tinker with it... It wasn't a Support Item, just an idle fancy of hers to give a toaster the ability to bring toast to its owner... Whatever reason she had for that particular idea.

The toaster proceeded to go haywire and essentially audition for a facehugger role in an Alien movie... With Kirishima unwillingly auditioning as the victim. "GetitoffgetitoffGETITOFF!" he was shrieking in a manner he would later chide himself for, considering it unmanly. Izuku was frantically trying to pry it from his face as Mina laughed hysterically at her friend's misfortune, Izuku even using five percent of One For All as he tugged. Even with his Quirk, it took more effort than he was expecting, noting that Mei had clearly had solid craftsmanship... Despite some clear software issues...

Ten minutes after that, she got bored of studying again, and fiddled with a couple spinning tops... Which proceeded to go haywire and sprout blades as they spun rapidly like little buzzsaws, one of them shooting at Momo, who skillfully dodged, though deliberately allowing it to leave a cut along her top and bra, giving everyone a good flash of underboob from her.

The last straw came another ten minutes later... They didn't even know what she had decided to tinker with this time, all they knew that one second, the desk she was at was totally fine, the next, she had said, "Oopsie!" and the desk was now on fire!

"Nobody panic!" Iida shrieked, clearly disregarding his own advice as he ran for the fire extinguisher, and quickly put out the flames.

After that, the whole group proceeded to dog pile Mei, in an effort to get the duffel bag from her. It was quite the challenging endeavor: she put up one hell of a fight. "No! My babies!" Mei shrieked comically, held in a Full Nelson by Ochaco as Tokage finally walked away with the bag, holding it a detached arm's length from herself, clearly on edge from handling it. No one could blame her in the least.

(This one took a bit... I admittedly couldn't stop laughing as I typed it out XD.)