They aren't friends because of Izuku being a nerd and Denki being a jock along with his friends Katsuki Bakugou and Kirishima Eijiro. Izuku's friends Tenya Iida, Ochaco Uraraka, Asui Tsuyu, Shouto Todoroki and Jaye Uchiga was nerds but not that nerdish as Izuku. Once Izuku bumped into Denki, Izuku fell in love with a muscular yellow hair jock with bright yellow eyes