He was at the age of 4, when it began.

A bunch of kids were huddled together at a nearby playground, each of them excited and bouncing around. One kid stood out amongst the rest: Katsuki Bakugou, as she stood at a slightly higher makeshift stage (it was actually a random hollow wooden box. What it was built for, no one ever knew), arms akimbo, sporting a proud grin. "So, extras." She started, hearing a few groans and complaints coming from kids who did not consider themselves as 'extras'. "Anyways, the reason I gathered you all here, is because... I can write in Kanji now!" Although having slow reactions, the children 'wow'ed and 'woahhhh'ed in amazement. One in particular was not afraid or hesitant to show his feelings. "WOW!! That's so cool Kacchan! You're so quick at learning!" A boy named Izuku Midoriya exclaimed, making the sandy-haired girl to blush while looking down. "I did it for you, Izu..." "What was that, Bakugou?" Immediately she replied with, "N-Nothing!!" She then fake coughed into her left hand that curled into a fist, (something she saw her daddy do) to get back to the point. "So, let's start with Izuku!" The boy whose name was called out pointed at himself in disbelief, before yelling out loud with a "YESSSS!!!". Bakugou proceeded to ignore this, knowing her friend could get overwhelmed by emotions easily. "So, the word 'Izuku', can be written as 'Deku' !" The kids opened their mouths in awe of the sheer coolness of the loud girl. Then... "That's great and all for Izu, but what does it mean?" Some random kid asked, freezing Bakugou into her current pose. She certainly hadn't thought about that. Crap, what should she do? "Yeah Katsuki, is there a meaning to Deku?" Another kid asked, which caused everyone at the playground (only the kids were there.) to burst with questions and opinions. Izuku just looked at the girl with hopeful eyes. Kacchan's probably already got an answer to the meaning! I mean, she's so cool! How can she not have thought this through?! Unfortunately, Katsuki didn't think it through, and was now panicking quietly. They all look up to me... yet I can't give them an answer... Now they'll doubt of me being their leader, and I'll soon be alone... I'm so stupid...so useless...so worthless... so- "D-Deku means worthless?" A shaky and unsure tone broke Katsuki's line of thought. She quickly stared at the kids carefully, before finding the source of the voice. Izuku Midoriya, who had a shocked smile stuck onto his face, barely managed to croak out the question loud enough for most of the kids to hear. But, one kid got his message. Damn it, I accidentally blurted the word out, and now Izuku hates me... No! I can't take back what I said, so I'll use this chance! I'll protect you, Deku. "Yeah! It means useless! Got a problem with that?! You loser!" She cursed herself for the hurtful insults, but kept going. "Deku from now on, means someone who is useless, and worthless!" Izuku could only stare at the girl he was childhood friends with, as her yelling influenced other kids into her example until every kid was yelling at him. Unable to take any more, the green-haired boy shut his eyes to squeeze the tears out while running home to his house. The kids didn't pursue him, though some intentionally raised their voices while mocking him. Katsuki stared at her only true friend's body getting smaller as he ran further. I'm sorry, Izu... but this way you won't get hurt.