Denki was your boyfriend, he had brought you to a concert, the guy singing had called you up to the stage, you gladly accepted. He started putting his hand on your waist and calling you his girlfriend/boyfriend which pissed off Denki

"Hey..hey! HEY!" He yelled to get his attention, he soon got into a fight with him on stage in front of people, you just stood there in shock as he punched the poor guy