Rin is the younger brother of Sae Itoshi, who started playing football with him at a young age. He has played as a forward on every team he was on and has always been regarded as one of the top players. He is regarded as Blue Lock's best player until he is officially confirmed to be by Jinpachi Ego at the beginning of the Third Selection. Rin's main goal is to become the world's best striker. He used to be fixated on defeating his brother in football and in turn, getting revenge.