Isagi Yoichi.

Yoichi Isagi (潔いさぎ世よ一いち, Isagi Yoichi?) is the blue lock member. Isagi is a second-year high school student who played as a forward for the Ichinan High School football team. When he arrived at the Blue Lock facility, he became a member of Team Z for the First Selection. Unlike his fellow competitors, who were handpicked by Anri Teieri after watching them play, Isagi was chosen personally by Jinpachi Ego himself after seeing him play. Isagi's main goal is to become the world's best striker.

Isagi is a teenager of slightly above average height and muscular build, developing a stronger, more defined-looking physique. He has short, dark blue hair that leaves a V-shaped fringe between his deep blue eyes. While attending Ichinan High School, he wore an unbuttoned blazer over a white undershirt and striped tie. Both the Ichinan High jersey and gym uniform are light-colored with black stripes. At Blue Lock, Isagi wears the standard-issued body suit (black with blue stripes) and tracksuit. During the First Selection, he wore Team Z's blue #11 jersey and Team Z's gray-capped cleats. During Second Selection, he wore Team White's #15 jersey and later switched to red. He then later switched to Team A's black #15 jersey during the Blue Lock Eleven tryouts. Isagi dons an official blue-colored Blue Lock player uniform with the #11, that looks very similar to the ones seen in the first cover spread minus the Japan flag during the Japan U-20 match.

Isagi is easygoing and has a generally friendly, cheery personality, but his simple and innocent habits often get on the nerves of the people around him. He tends to avoid any childish squabbles among other Blue Lock competitors and tries to be a peacekeeper between his friends and rivals. At the beginning of Blue Lock, Isagi is massively unsure of himself and his skill due to being the second-lowest-ranked player in Blue Lock initially and his conflicting ideas of football. As time goes on, Isagi develops a more assertive presence on and off the field, becoming the foundation for Team Z and garnering the respect of some of the best players in Blue Lock, who mostly have heavily assertive or dominant personalities. As of Third Selection, Isagi has the confidence, charisma, and reputation to talk openly with Rin Itoshi, one of the most talented yet difficult people in the Blue Lock Project. Initially, Isagi was unsure on how to proceed in Blue Lock due to being taught an ideology during his time in high school that conflicted with what was being promoted in Blue Lock, as well as being unsure on how to be egotistic. However, starting with Team Z's first win and subsequent wins thereafter, Isagi becomes well-acquainted with the rush of victory and the cold ruthlessness needed to survive in Blue Lock. As times goes on, he becomes willing to step on the plans and dreams of his opponents and teammates in order to score a goal and go further in Blue Lock. When it comes to football, he is ambitious and calculated, willing to change and adapt, to get the right "chemical reactions" out of his teammates, to stay a step ahead of their opponents, and be the best player on the field, staying true to his commitment to becoming the world's best striker. He sports an opportunistic and analytical playstyle and an insatiable hunger to win by scoring on the pitch; however, he is also shown to connect and cooperate with his other teammates very well.

Forwards: also known as strikers, have the main objective of scoring goals. They are often the players who get the most attention since their role is designed to be in a scoring position. They also take part in penalty kicks and corner kicks when the opposing team kicks the ball out-of-bounds. They are normally the players in charge of starting off the game at the start and halftime. Raumdeuter: The word essentially translates to "space investigator" and is best used to define the effective role when exploiting the half space. A Raumdeuter's main function is to drift infield and find pockets of space in which to thrive; it is essentially a player who locates dangerous areas of the pitch and uses unoccupied space to create confusion among opposition backlines. They are limited dribblers and are not characterized by their pace. Their first touch is very efficient and is a huge contributor to their set-up touches prior to scoring. Isagi creates ideal plays and chance opportunities by using his spatial awareness to view the field as a whole and the players on it. With his understanding of all the players, he uses his off-the-ball movements to occupy empty spaces or create dangerous ones to form ideal plays for his teammates, chance opportunities using his teammates, and to score high-level goals for himself. With his reflex and enhanced vision, Isagi is able to create plays only possible for himself. Due to his relationships and game time with most of the prominent Blue Lock players, Isagi is able to bring the best out of his teammates by either forcing them to perform plays so he can attack or by pushing themselves to exceed Isagi's evolving skill. By the time of the Neo-Egoist League, players are willing to follow or use as a guide Isagi's style of play, cementing his place at the top of Blue Lock. He has been noted to be the heart of Blue Lock by Sae Itoshi and implied to be that by Ego.

the blue lock is a training facility built to attract top Japanese soccer players who will live in the facility and follow a strict training regimen designed by Jinpachi Ego himself. The center of the facility also contains a soccer arena that is used to host professional matches. There are five stages in the project, but only one player will be able to complete it. The player who makes it to the end of the project will become a bomber in the Japanese league. Players who are eliminated from the project will be barred from the Japanese league forever. New challenges are constantly appearing in the Blue Lock, which eliminate a huge number of players. The building is a massive structure that takes up the entire area of a large cliff in the mountains of Japan and reaches the height of a skyscraper. The building is shaped like a pentagon and is thus divided into five separate sections. Each section is designated as a stratum, and the stratums contain a variety of different rooms, including living quarters, a dining hall, gyms, dedicated training rooms, several soccer training pitches, a soccer arena in the center that can host professional matches, and even enough space to host multiple training sessions simultaneously.