Nagi

"It's the first time I've felt like this, and to understand this 'frustration,' I want to play soccer with this guy. I want to try... to push myself a little..." Nagi to Reo

Seishiro Nagi is a former competitor of Project Blue Lock and the titular protagonist of the spin-off, Blue Lock - Episode Nagi, who played as a right winger for Manshine City in England during the Neo Egoist League.

Upon arriving at Blue Lock, Nagi was a member of Team V and the best player in his category. After the Blue Lock Eleven team played against the Japanese under-20 national team, Nagi was ranked as one of the best players in the project. However, he was sidelined during the Neo Egoist League when his ego and motivation began to wane after defeating Yoichi Isagi in a one-on-one duel.

After his expulsion, Hirotoshi Buratsuta offered Nagi the opportunity to participate in a selection process to try and regain his place in Blue Lock, but he initially refused. However, after much reflection, Nagi decided to seize the opportunity to achieve his new goal: to become the best striker in the world at any cost, even if it meant betraying and destroying Blue Lock.

Appearance Nagi is a tall young man with a lean, muscular build. He has medium-length white hair with a V-shaped fringe framing his eyes. His eyes are gray with large irises.

During his high school years, Nagi wore a school uniform consisting of a white blazer with a cascading star pattern on the collar, although underneath he wore a dark sweatshirt instead of a dress shirt and tie. He also wore dress pants and dress shoes.

In Blue Lock, Nagi wears the standard jumpsuit (black with gray stripes) and tracksuit. During the First Selection, he wore jersey number 11 for Team V, and during the Second Selection, jersey number 7 for Team White.

Personality Nagi is a very lazy and unmotivated person with an exceptional aptitude for soccer. He possesses supernatural talent, with incredible reflexes, good speed, and jumping ability. But, initially, he shows no interest in becoming a professional or even playing. As long as he can get a decent job and continue leading a quiet life, he is content to do nothing forever and frequently displays lethargy in his speech and body language. Extremely introverted, he lives alone in an apartment paid for by his parents, having only a pet cactus for company. Before meeting Reo, he had no friends in high school and was frequently the target of gossip and possibly bullying. Even so, he shows no interest in socializing and often needs to be dragged into things by others, especially Reo. Initially, he doesn't want to put in the effort in soccer and looks down on those who are weak and untalented in the sport, since these things are easy for him. He doesn't even know anything about the best soccer players in the world, much to the chagrin of his competitors. Initially, he appears indifferent to football and the dream of becoming the best striker in the world, preferring to play video games or simply skip training. He exhibits typical reclusive behavior and may even be addicted to his cell phone. He resists letting go of the device when Anri tries to confiscate his belongings, and Reo even bribes him to play, reminding him that he can get it back with the goal reward system.

Despite all this, Nagi demonstrates that he can stay motivated when challenged. Upon entering Blue Lock, he encounters players who draw him so deeply into the game that he is willing to create his own strategies and confront Reo, whom he normally obeys, just to be able to think as little as possible.

Nagi also possesses a bold side that manifests more frequently around Baro, due to an old rivalry that began when Baro called him Reo's "slave." He often antagonizes and confronts him when his arrogance irritates him, something few characters dare to do, considering how intimidating Baro can be. But when he wants to play, he demonstrates a deep sense of teamwork and manages to create synergy with many players, especially Reo and Isagi. Although Nagi may seem apathetic, he is a reliable player who possesses some of the most unpredictable moves on the field; perhaps only Gagamaru rivals him in terms of creativity.

After playing against Team Z in the final of the First Selection and suffering his first defeat, Nagi begins to take more initiative and deal with the frustration of the loss. He finally starts to find motivation and is willing to explore these feelings alone if necessary, and this only happens because he realizes that his friend and teammate, Reo Mikage, seems lost against Team Z. Despite his initial apparent indifference, Nagi strives to improve his soccer skills as a result of his team's defeat to Yoichi Isagi. This desire to improve accompanies him in later arcs, and he even jeopardizes a friendship because of it. During the Neo-Egoist League, defeating Isagi was Nagi's main motivation.

Nagi seems to care about his friends and teammates, especially his best friend Reo, although their relationship becomes strained from the Second Selection onwards due to Reo's possessiveness towards Nagi, which obscures their shared dream of winning the World Cup. However, at his core, he is selfish like some of the best players in Blue Lock. He only cares about his ambition, his dream, and winning.

Nagi tends to clash with people he dislikes. When he meets Baro after Nagi and Isagi's defeat to Rin Itoshi, they immediately begin arguing and provoking each other, competing on the field to see who is the best, frequently challenging him to a 1-on-1 duel, exchanging insults, and even fighting over who gets the single bed in a room for teams of three.

After being locked in the Blue Prison and returning to school life, Nagi regrets his previous laziness, becomes extremely frustrated with his "inability to change," and misses his "energetic version of himself." He begs Anri to let him return, demonstrating his desperation to go back to the Blue Prison, but is rejected for being an "outsider."