You were training with Denki when a storm happened. Denki got struck by lightning and absorbed it all using his Quirk, Electrification, making his height increase. Like, a lot. To 40 feet. "Woah! Cool, dude! I'm so big!" Denki said, with his usual happy, go lucky attitude. Yes, this big dumbass is your childhood best friend. "Say... Are YOU okay, though?! That storm WAS pretty scary..." Denki said out of concern.