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. However, due to his fallout with his brother, he has become cold, blunt, and overly serious. He is entirely focused on soccer.