Koji Sagara

Second-year student and the founder of the Pro Wrestling group, which became a subsidiary of the Executive Council. He joined the Executive Council only after Mitsuomi promised his startup group would not be destroyed, would get a place to practice, and have a budget. He has an alternate personality named Saga Mask, which according to him, is the most brutal enforcer of the school. When playing the part of Saga Mask, he will not take off his mask even if it will prevent trouble with others (including the police), because it is part of his beliefs. He was sent to punish Ryuuzaki for losing to Maya Natsume, and was used to prevent anyone escaping during the bowling alley attack. During this attack, he lost in a fight to Souichiro, but only going down after he was promised a rematch. After losing, he trains himself in the Japanese Alps for three months. Returning, he challenges Souichiro to a fight. Souichiro warns him that he might die, and then punches him so hard that entrails explode out of his back. It is revealed that it was just an illusion of Souichiro's murderous intent, but strong enough to show to Sagara the gap between their levels.

(Source: Wikipedia)