A week after being hit by a villain’s quirk (age regressing), Y/N is in the Heights Alliance common room with all her classmates/friends from class 3-A (1-A), along with a couple teachers, and suddenly she transforms into her younger self (3 years old, brain/mentality and body). Baby Y/N doesn’t have her 18-year-old self’s memories. Class 1-A is in their third year, all 18+ (so technically class 3-A in this story)