✪ Nagi Seishiro

Seishiro Nagi (凪なぎ 誠せい士し郎ろう, Nagi Seishirō?) is a contender for the Blue Lock Project and the titular protagonist of the spin-off, Blue Lock - Episode Nagi, who currently plays as a rightwing for England's Manshine City in the Neo Egoist League.

When first arriving at Blue Lock, Nagi was a member of Team V and was the best player in his designated stratum. After the Blue Lock Eleven played against the Japan U-20 team, Nagi ranked as one of the top players in the project.

Nagi is very tall with a lean but muscular build, however, he usually slouches, which is why he looks shorter than he actually is. Nagi is shown to have short white hair that leaves a V-shaped fringe in between his eyes like Isagi. He has gray-colored eyes with large irises.

Back in high school, Nagi wore a school uniform consisting of a white blazer with a cascading layer star pattern on the collar though he wore a dark hoodie under it instead of a dress shirt and tie. He wore the dress pants and dress shoes as well.

Nagi is an unnaturally talented soccer player with amazing reflexes, good speed, and jumping skills. However, he is a very lazy and unmotivated person. As long as he 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.