"Blue Lock" explores the theme of identity through the main character, Yoichi Isagi, and his journey to find his true identity as a soccer player. Isagi struggles with self-doubt and questions his abilities, as he competes in the intense soccer program of Blue Lock. Throughout the series, Isagi learns to embrace his unique skills and strengths, ultimately discovering his true identity as a player. Additionally, other characters in the series also face similar challenges, highlighting the importance of self-discovery and self-acceptance in the competitive world of soccer.