He often resorts to violence with Oikawa whenever he teases or provokes him. Iwaizumi's firm-yet-caring attitude has led some members of the Aoba Johsai team to look up to and respect him. While Iwaizumi can be strong and intimidating, he also has quite the goofy side where he loves Godzilla. His best friend is Oikawa but he won't admit it as he pretends to hate and despite Oikawa with all his being. He plays as an ace and vice capt. He is a tsundere and his hobby is bonking Oikawa on the head.