Kengo Mizumachi

Mizumachi is a blonde-haired lineman, the third-tallest (203 cm) player on the Poseidon and a natural athlete. He is a first-year player who, in middle school, was on the swimming team, but he quit because his teammates were unwilling to match his dedication to winning the championship. Along with being incredibly energetic and naturally athletic, Mizumachi possesses a childlike innocence and is almost always optimistic. However, Mizumachi is also immature, and he has a bad habit of saying or doing disrespectful things. He thinks very highly of his abilities, and at first he believes that tall, slender players like himself are the future generation of American football players. Initially, this causes him to think little of opposing linemen of short stature, such as Onihei and Komusubi, and in fact he believes that Komusubi should leave the Devil Bats so as not to be a burden to them. When he is challenged and defeated by Komusubi in the game with the Devil Bats, Mizumachi changes his opinion of shorter opponents. On the other hand, he holds deep respect for the seniors on the Poseidon team, all of which are quite short compared to himself. He even criticizes the Devil Bats, claiming the Poseidon deserve to win because they have a great deal of third-year players on their roster while the Devil Bats have none. When the Poseidon are defeated, he cries because the seniors will never be able to play in the Christmas Bowl. He later appears at many of the Devil Bats' matches as a spectator, and also helps the team prepare for the Christmas Bowl by serving as Kuroki's personal coach.

While a powerful opponent, Mizumachi's lighthearted personality is generally used to comedic effect, along with his tendency to strip down to his boxers for no apparent reason. Still, Mizumachi is an incredibly athletic player, able to use his great height to his advantage in games. He is also very agile for a player of his size, and outside of American football he is a very fast swimmer and capable of pulling consecutive somersaults. Though Mizumachi is not exceptionally powerful, his great height and long limbs allow him to gain leverage on shorter linemen, while his slim build makes him faster than most player of his height. Though a rookie to American football, Mizumachi's experience in swimming grants him practice in the use of his two signature techniques. His explosive "swimmer's start", in which he assumes a competitive swimmer's stance on the starting block, lets him burst forward quickly at the start of the play, while the swim move, which is similar to his chosen swimming style, the front crawl, helps him to push opposing linemen aside. He can also serve as a fourth linebacker along with Kakei, Ohira, and Onishi when the Poseidon use their "Poseidon" formation. His prowess earns him the distinction of being named one of the best five offensive linemen at the end of the Autumn Tokyo Tournament.