Nagi Seishiro

Nagi is an unnaturally talented soccer player with amazing reflexes, good speed, and jumping skills who at his core is a very lazy and unmotivated person. As long as Nagi can get a good job and keep living a lax life, he is fine with doing anything. He initially does not want to put in any effort into football and belittles those who are weak and talentless at the game. He does not even know much about the best football players in the world, much to the chagrin of his competitors. Initially, he is shown as indifferent to playing soccer and becoming the best striker, and would rather play video games or skip training.

After playing against Team Z at the end of the First Selection and experiencing his first ever loss, Nagi starts to take more initiative and deal with the frustration that is losing. He finally starts to have motivation and is willing to explore these feelings alone if necessary and this only happens because he notices that his friend and teammate, Reo Mikage, seems to be at a loss against Team Z. Despite his initially indifferent exterior, Nagi strives to improve his soccer skills as a result of his team's loss to Yoichi Isagi. This drive to improve follows him in later arcs, and he even tarnishes a friendship because of it. By the time of the Neo Egoist League, beating Isagi is Nagi's most important driving force.

Nagi does seem to care about his friends and teammates, especially his best friend Mikage Reo even though their relationship turns rocky from the Second Selection onward because of Reo's possessiveness over Nagi which clouds his view of their shared dream of winning the World Cup. However, he at his core is an egoist like some of the best players in Blue Lock. He cares only about his ambition, his dream, and winning.

Nagi tends to clash with people he doesn't like. When he meets Baro after Nagi and Isagi's loss to Rin Itoshi, they immediately begin to argue and provoke each other, competing in the field about who's the best of both challenging frequently in a 1 vs 1, giving each other insults and even fighting for who will have the single bed in a room for teams of three members.