Sena is the main protagonist in the manga and anime series Eyrshield 21. He is a dynamic character who, at the start of the series, willingly becomes a gopher for other people to avoid being bullied more. By becoming the running back and the ace of the Deimon Sena matures and becomes braver, and becomes willing to place himself in danger of physical harm in order to achieve his goals. He is a first-year Japanese high school student. A major element of the series' plot is the revelation of the history of the title "Eyeshield 21", which Sena is forced to use as a secret identity for much of the series. He is the main rival of Seijuro Shin of Ojou White Knights.
Due to his diminutive stature and weak outward appearance, Sena was bullied by his peers in primary school, Riku Kaitani taught Sena how to use an explosive run to get rid of them. However, Sena used this run to become a gopher for others instead of getting rid of bullies. Unknowingly, this allowed Sena to build up his running and dodging ability.
Soon after entering senior high school, Sena was forced into playing American football by Hiruma. Hiruma had seen Sena running away from the Ha-ha brothers, who wanted to beat him up, and recognized Sena's running ability. To conceal his identity, Sena wears a green colored eyeshield to cover the upper part of his face during practices and matches. In the manga, the color was later changed to blue when Hayato Akaba of the Bando Spiders gave Sena his eyeshield, relinquishing the name Eyeshield 21. Hiruma picked the alias "Eyeshield 21" after an ace Japan player of the same name in the United States of America, so that Sena could have a secret identity and thus not be recruited by other athletic clubs.
Although a bit of a coward, he is a kind and chivalrous guy. He once tried used his speed to protect Mamori against Agon, and during his Death March, he twice tried to protect Suzuna from falling. When Agon made fun of Hiruma and Kurita's dream of going to the Christmas Bowl, he became infuriated, and for the first time in his matches, he tried to attack someone head on with destructive intent. He is also the first one who tried to knock some sense into Monta when he devastated about the fact facing the son of his idol, Taka Honjo of the Teikoku Gakuen.
- Normal Running & Cuts: This was Sena's method of running at the beginning of the series, gained during years prior when he was a gopher for bullies. He is able to attain a rocket start, as well as make very sharp turns and cuts. However, in the beginning his speed decreased after the explosive start so, before training with Deimon, his 40-yard-dash is 5.0 seconds. If he's pressed to a certain emotional level, his time shortens to as little as 4.2 seconds (see Speed of Light Pace).
- Change of Pace: This was Sena's pattern of running up until after the game of the Nasa Aliens. This involves him running at relatively easy pace, then suddenly accelerate to full speed. However, by doing so, Sena stops for a moment when making a turn allowing himself to be tackled. He manages to overcome this problem after enduring the Death March by learning the Devil Bat Ghost.
- Speed of Light Pace: This is Sena's ability to run the 40-yard dash in 4.2 seconds, considered to be the highest a human can go. Initially, Sena can only go this fast once per game since after doing so faints out of exhaustion. However, in the match against Bando Spiders, he manages to overcome his limits and manages to hold his top speed for a much longer period of time. By the beginning of the Kantou Tournament, Sena is able to run at this pace frequently without rest, but as shown in the Nagas game, doing it too often can make his legs useless.
- Speed of Super Light Pace: Shin estimated for Sena's Final Play against him that he was able to run a 40-yard dash in 4.1 seconds by using Shin's arm as a propellant. Its name was christened by Shin, and is only used in the final play against the Ojo White Knights in the fall tournament.
- Foresight: A technique first developed for running errands, Sena is able to deduce the amount of movement, as well as any openings people might leave unguarded allowing him to find the best place to run. He first uses this technique in actual gameplay against the Koigahama Cupids team when he returns the final kickoff of the game for a game winning touchdown. This also helps him to determine which way he could play being a quarterback, either to do pass or run. However, its main weakness is that it can't anticipate the moves of an incoming opponent if they are moving at the same rapid pace as Sena at his topmost speed, forcing Sena to improvise when facing other speedy players like Shin, Riku or Panther.
- Scramble and Pass: In the quarterback position, Sena takes the ball after the snap and rushes toward the sides. He then makes a short, awkward pass toward any eligible receiver. The trajectory of the ball is described as horrible by Ikkyu, though in practice it works for Sena, as the opponents can't tell which way the ball is heading.
- Devil Dragon Fly: An adaptation of Shinryuji's trademark play, both Sena and Hiruma play as quarterbacks. Either quarterback is able to receive the snap, and the number of plays, such as lateral passes between quarterbacks and passes to receivers, are increased greatly as a result. Unsui comments that the way Deimon played this formation is different, but definitely has the shape of the Original Dragon Fly. Used it manga chapter 270.
- Christ Cross: Another running play, Monta and Sena cross paths with the quarterback (Hiruma) as their center. This hides the true ball carrier, as any of the three players may have the ball after crossing. However, The first time this play is attempted, Monta and Sena fumble the ball.
- Devil Cross: The "warped" version of Christ Cross, in which the ball carrier laterals the ball toward the quarterback after luring the defense, giving the pass play more options and freedom.
- Devil Bat Ghost: A technique in which Sena is able to use a crossover step to make a sharp cut without slowing down. He learned this after enduring the 2000 km Death March by kicking a stone pebble and running simultaneously which teaches him how to increase his steps without slowing down. Its effect creates a kind of blurry afterimage which confuses opposing blockers, causes them to misjudge his speed or tackle the afterimage created by the move. By episode 46 of the anime, in a match against Shin, Sena discovers the strain of the Devil Bat Ghost has on his knees, which he soon overcomes with constant practicing which allows Sena to use Multiple Devil Bat Ghost Bursts. Later, his Devilbat Ghost evolved so much, that he able to practically creating shadows and moving at complete 360 degree at will, makes him near impossible to get touched. Just like Shin said, "Even with all power in this world, it's no use against a speed you can't touch".
- Multiple Devil Bat Ghost: In chapter 287, after witnessing "true" Ghost Steps performed by Yamato, Sena manages to perfect his own Devil Bat Ghost using a combination of violent crossover and simple cut steps, creating four ghosts.
- Devil Bat Dive: Inspired by his desperate dive into a closing train to escape from the Hah Brothers in the first chapter, Sena rushes toward the scrimmage line at top speed, then jumps over the opposing linemen in a corkscrewing motion. This is a very dangerous maneuver and even Hiruma initially forbids him to use it more than once or twice per game, and only for a clinch point, as it could easily cause injury to Sena.
- Sky Devil Bat Dive: An alternate version of the Devil Bat Dive where Sena is first placed at the end of the scrimmage line. Hiruma then rushes the opposing line as Sena makes a fast reversal and jumps upward as Hiruma laterals upwards the ball to Sena.
- Fake Devil Bat Dive: Unlike the regular Devil Bat Dive, this involves Sena jumping over opposing players while pretending to carry the ball. The technique is intended to fool the opposing team in stopping his charge while the real carrier of the ball gets through. This was first shown during the game against the Wild Gunmen, and last seen against the Dinosaurs.
- Double Devil Bat Dive: Sena rushes toward the goal line then jumps over the defending linemen like in a regular Devil Bat Dive, but then passes the ball in midair to Monta who is in the endzone.
- One Man Devilbat Dive: Using this, Sena only dives over a single opponent. In its first use against Shin Seijirou, Sena combined it with the Devil Bat Ghost and Stungun.
- Extremely Low Altitude Devil Bat Dive: A combination attack with Komusubi, using the small lineman's power and Sena's ability to fly over a low-gravity opponent such as Gaou. Used only once against the Hakushuu Dinosaurs, and succeeds only when Kurita intervenes to prevent Gaou from crushing Sena and Komusubi.
- Spin Move: A regular move which Sena used to evade Togano in the first chapter. While running forward, he evades enemies' tackle or block by swerving to the side, spinning his body to gain momentum he needed to break or escape a block or tackle.
- Devil Bat Tornado: Also called the Devil Bat Hurricane, this was created during the game against the Kyoshin Poseidon by combining the Devil Bat Ghost with a spin Move. Its effect not only causes an afterimage to appear, but also adds rotational force, making a two-handed tackle less effective.
- Devil Light Tornado: Also called the Devil Light Hurricane, this combines the Devil Bat Tornado with the Speed of Light Pace. In chapter 217, Sena uses this in an attempt to evade Shin's Trident Spear Tackle. However, Shin, with his own Speed of Light Pace and the extra speed of the Trident-Spear Tackle, manages to tackle Sena. However, it is also not as effective against close defensive attacks such as Marco's Screw Bite.
- Vertical Devil Light Hurricane: Sena collides into his opponent head-on, then pushes upward while rotating at the Speed of Light Pace. Using the opponent's body as a pivot, Sena rolls past and forward, thereby evading any attacks. Being so close prevents an opponent with a close defensive attack like the Screw Bite from getting his hands around the ball.
- Stiff-Arm: A normal defensive move used to keep an opposing player at a distance. By sacrificing ball safety, Sena can extend one arm to ward off a blocker. This was first done against Agon in the game against the Nagas and Sena was able to topple Agon by pushing against his helmet.
- Devil Stungun: In chapter 229, by using his arms, Sena is able to partially deflect Shin's Trident-Spear Tackle. His counter is likened to a foot soldier using the point of his sword to redirect the trident of a charging horseman away from him, rather than meeting the attack head on. Just like a similar move used by Patrick "Panther" Spencer of the NASA Aliens, this move sacrifices ball safety for a chance to break through (Doburoku: "When you had twice the chance to break through your enemy, the chance of the ball being lost is 10 times greater"). Unlike the basic Stiff-Arm, this involves a jabbing motion.
- Sagittarius: Inspired by the team strategy of the same name used by Shin and Sakuraba of Ojo, the Deimon version is first seen in the Hakushuu game. This combines the Devil Stungun and the Devil Backfire, and Sena becomes Monta's guard as the latter catches a pass.
- Devil 4th Dimension : Sena's ultimate technique of running, created during the Christmas Bowl against the Teikoku Alexanders. While running at his Speed of Light pace, Sena takes one quick backstep without changing his speed or stance. This makes the defender lose control of his tackle thinking that Sena "turned back time". During the International Youth Cup semifinal match against Germany, Sena takes only a half-step back as a feint before he changed his run in order to defeat Germany's star player Schultz. However, the weakness of the Devil 4th Dimension is that for a moment after the backstep, there is a brief period of time where Sena lags. A defensive players can take advantage by stopping their own movement while facing the backstep, going for the kill at exactly the right moment. Yamato chose to defeat the backstep by sealing it with his Caesar Charge, using his strength to increase his speed to super-light levels, completely overrunning Sena.
- Devil Bat 4th Dimension Ghost : Sena removes the weakness by combining the Devil 4th Dimension Run with the Devil Bat Ghost, confusing the blocker's perception at the moment of lag. After seeing this move, Yamato mentioned that no amount of strength or talent could overcome this technique, since it is "genuine speed".
Sena was always teased and bullied through elementary school because he relied on his childhood friend Mammori Anezaki to protect him. In fourth grade, he met Riku Kaitani who decided to teach Sena his running techniques, which Sena absorbed quickly. At first however, Sena used his new running ability to run errands for others, much to Riku's disgust and anger. After a while, Riku moved away, and Sena still used his speed to help carry bags and buy food for others. Ironically, this running helped Sena develop his dodging and running skills.
Sena made it into Deimon High School where he continued to be a gopher for others. On the first day, he enrages the Haha brothers who decide to teach Sena a lesson in the American football room. They become distracted and start messing around with the equipment instead, just as Kurita breaks in, asking if any of them would like to join the football team. After trying to tackle Kurita, the three Haha brothers are tossed out by Kurita, who believes he is simply showing them a linebacker move. The thugs later try to take revenge on Kurita and harrass Sena for his number, who flees from the three Haha Brothers. Meanwhile Hiruma, the devilish quarterback of the Deimon America football team sees Sena'a potential and forces Sena to join the team.
Sena decides to stay on the Deimon American football team because he finds it fun. Soon, Hiruma manages to recruit a full team for the tournament. The team hope to be in the top three teams of Tokyo to advance to the Kanto tournament and finally the Christmas Bowl. The Christmas bowl is the match for the best high school American football team in Japan. Through many hard games Sena and his team finally manage to advance to Christmas Bowl and win. Throughout the games Sena improves his running skills and learns many techniques to become the best running back he can be. He becomes the MVP of the Kantou tournament.
After winning the Christmas Bowl, Sena, Monta, Yamato and Taka, the best receivers and running backs of Japan are called to build a national team. The four split up to find teammates that can create the best Japan Team possible for the International Youth American Football tournament in New York. Japan beats Russia and Germany to finally advance to the finals. There, they meet up with America, the favorites of the tournament. Japan manages to tie America by the end of the game, something no one thought was possible.
Two years later, it is shown that Sena had been playing for Notre Dame in America during the final half of his last year in Deimon. He returns to Japan to attend Enma college, and faces off against some of his former teammates who attend different colleges as they all compete to go the Rice Bowl, the match between the best college American football teams.
World Cup Rematch vs PathnerEdit
Sena is tasked, along with Monta, Yamato, and Taka, with recruiting the players who will form Japan's all-star team in the American Football Youth World Cup. After meeting with Shin, Gao, and Agon, Sena and Monta set about recruiting the best players from Kanto. Once all of Japan's starters are chosen, however, Sena requests that those not recruited be given the chance to join the team, leading to tryouts being held to determine Team Japan's bench players. Shortly after, Sena and the rest of Team Japan travel to New York City to participate in the Youth World Cup, but the team's starters are unable to play in their first game against Russia because Agon has stolen their jerseys as part of his plan to gain an edge in the MVP voting. Sena rushes to retrieve the team's jerseys from where Agon has hidden them along with Shin, Riku, and Yamato, but he is separated from the other three while returning to the stadium. Because of his mistake, Sena witnesses the end of the game between Finland and Militaria at a different stadium. The rest of the team arrives after Japan's surprise bench players defeat Russia, and all of them are spectators for Team USA's first-round game with New Zealand. There, Sena reunites with Panther, who has become a member of Team USA's Pentagram and evolved into an even faster runner than Sena with a 40-yard dash of 4.1 seconds. Prior to Japan's game with Militaria, Sena and Suzuna spy on Agon and overhear his attempt to force Kid and Hiruma to allow him to play in the quarterback position. Sena serves as Japan's main weapon in their blow-out win over Militaria, but because of how easily this victory becomes, Sena finds himself unable to get excited during the game. He does find a worthy opponent in Japan's next game against Germany, in which he faces off against and defeats Heinrich Schultz to lead Japan to victory 34-24.
Japan advances to the final round of the World Cup, where they are to meet Team USA to play for the championship. Sena attempts to emulate Panther's running style, but finds that doing so actually slows his pace because his short legs are unable to match Panther's long strides. Understanding that he will be unable to match Panther's speed, Sena grows anxious, and has trouble sleeping the night before the game with Team USA. He has a conversation with Sakuraba about the physical limits of those who are not born with innate talent, and the two wonder how such players could possibly compete with hard-working, talented opponents. Early in the Japan-USA game, Sena faces Panther in an individual confrontation. Sena is able to pass Panther by chaining together the Devil 4th Dimension, Devil Stun Gun, Devil Light Hurricane, and a stiff arm to push Panther to the ground, but even when Yamato briefly blocks him, Panther manages to tackle Sena from behind. Realizing that Panther will always be able to chase him down from behind even if he is passed, Sena begins to despair under the revelation that he may be totally incapable of winning. Later in the game, when Panther disrupts Hiruma and Agon's attempt to use the Dragonfly by blitzing, Sena asks to be allowed to blitz Clifford in the same way. Hiruma allows him to participate in a three-man blitz along with Agon and Shin, and Shin successfully sacks Clifford and forces him to fumble the ball, which Sena recovers and returns for a touchdown. Sena later forces a fumble of his own after Habashira enters the game to replace Shin; when an American runner is distracted by Habashira who is persistently trying to tackle him, Sena is able to snap the ball away from behind, and Riku recovers the fumbled ball and also returns it for a touchdown. When Team USA relies on Panther's running to preserve their lead, Sena desperately attempts to stop his rival, but cannot do so, even when attempting to use Shin's Trident Tackle. During his struggles, Sena decides that even if he may never defeat Panther, he will continue to challenge him without hesitation. Eventually, Sena does manage to tackle Panther when he lifts himself back up off the ground immediately after falling after a missed tackle, headbutting Panther in the chest. Finally, Sena scores the game-tying two-point conversion when Team Japan uses the Cerberos Dive, a final variation of the Devil Bat Dive, and time expires quickly after this play to make the game's result a 45-45 tie. When both Team USA and Team Japan's players decide that they are unsatisfied with this result, the teams play an unofficial overtime, which begins with Sena playing as Japan's quarterback. However, the results of this unoffical overtime are unknown. and officailly both teams were declared champions of the tournament.
Sena continues playing for the Deimon Devil Bats in his 2nd year of high school, during which he serves as the team's new captain. He is additionally contacted by Clifford during his third and final year in high school, and is invited to play for Notre Dame High School, turning the last of Hiruma's lies about his identity into a reality. Sena then applies to and is accepted into Enma University, where he joins the football team. With former Devil Bats Monta and Kurita and former opponents Unsui, Mizumachi, Riku, and Kotaro as his teammates, Sena vows to play in the Rice Bowl, Japan's semi-pro and college-level championship game. He also vows to play in the NFL like Panther, who has won the Youth World Cup MVP title and joined with the San Antonio Armadillos. As shown in the anime he manages and successfully joins the NFL along with Hiruma, Shin, Yamato, Taka and others and he is shown playing in a game against Hiruma and Panther. He got invited to the NFL combine because he was on a Japanese National team in the High School World Cup because Panther won MVP and both teams won and the NFL to be good sports they decided they could come to the NFL combine once they were ready as result some Japanese players who were on the team got to play in the NFL.
Sena is a rather short and somewhat frail high school student, and is overall so small that he is frequently dragged or carried around against his will at the beginning of the series. He grows somewhat taller and more muscular as he physically grows through the course of his first year in high school and also trains his body by playing football. His hair is black with several streaks of brown, which are dyed. However his hair also seems to be naturally spiky and sweeping up and to the left, judging by how his hair had the same shape when he was a child.
For his entire life, Sena has been an extremely timid pushover. This begins to change as he matures through the series, largely due to his experiences playing American football. While Sena remains fearful of injury and is easily intimidated for the duration ofts confidently and never boasts about his abilities, and whenever he attempts to make a bold statement, he tends to trail off at the end as his own self-doubt and fear cause his countenance to fall apart. He does not usually grow angry, only doing so when peopleutlook usually contrasts with those of his more confident and reckless friends and teammates, such as Monta and Suzuna. Despite this negativity, Sena always becomes determined in the crucial moment of a match when he must surpass an opponent with superior abilities, and could be said to act appropriately when it matters most.
At the beginning of the series, Sena enters Deimon High School.Ha Ha Bros try to beat him up on the first day of school, but they are stopped by Ryokan, who subsequently becomes Sena's friend and tells him of his dream to play in the Christmas Bowl. Although Sena finds football to be frighteningly violent, he agrees to become the Devil Bats' secretary. The Ha-Ha Brothers again attack Sena while he walks home from school, but Sena decides to run rather than let himself be beaten up. Sena manages to escape, and Hiruma witnesses his running abilities and realizes that he has the potential to be a great American football player. The next day Hiruma forces Sena to join the team as a running back in addition to his position as secretary, and has him disguise himself and play under the moniker "Eyeshield 21". The reason for this disguise is to prevent him from being recruited to the other athletic clubs, but Hiruma also uses Sena's secret identity to bluff about his capabilities and intimidate their opponents.
Sena confirms Hiruma's suspicions about his potential when he sets the Japanese record for the 40-yard dash in 4.2 year and later scores the winning touchdown in his first football game on a kickoff return against the Koighama Cupids. Although he only participates in this single play, he decides that he enjoys playing football, and even refuses to leave the club when Mamori tries to take him away from it. Instead, Mamori ends up becoming the team's manager in order to assist Sena and better protect him from Hiruma; despite this, Sena decides to keep his being Eyeshield 21 a secret from her, believing Mamori would prevent him from playing. Sena helps the Devil Bats to grab an early advantage in their second game against theOjo by scoring a touchdown and tipping a pass for Hiruma to intercept, but this success is short-lived once Seijuro enters the game. Shin stops every single one of Sena's attempts to run past him, brutally stopping Sena using the Spear Tackle, and Oujou takes a tremendous lead. During the second half, Sena accidentally runs into Sakubara