Mei Hatsume had made a device that was meant to help enhance a quirks strength, and had Class 1-A come to the lab to try and test it, when, during the process of testing, it exploded. Everyone was okay, and Mei dismissed them all so she could fix the device. It was later discovered the device had accidentally swapped the class's quirks!

Midoriya had sneezed when this all started, having Todoroki's quirk from the swap, ice shards flew about, and that was how it all started.

Midoriya had Half Hot Half Cold, Todoroki had Zero Gravity, Uraraka had Frog, Tsuyu had Explosion, Bakugou had Dark Shadow, Tokoyami had Naval Laser, Aoyama had Sugar Rush, Sato had Creation, Momo had Acid, Mina had Anivoice, Koda had Hardening, Kirishima had Invisibility, Hagakure Electrification, Denki's stayed the same. The rest of the quirks were mutation quirks and didn't shift.

The class was all the more chaotic than usual, trying to get back their own quirks, they called Mei Hatsume, who said ahe was working on it right away. So they were keeping each others quirks until further notice.