Hiruma usually acts in a vulgar, bizarre, threatening manner so as to intimidate or disturb those around him into getting what he wants. He has a cunning, goal-oriented mind and does not seem to care what means he uses to accomplish those goals. His sense of morals is lax at best, but he is quick to find the moral flaws of others, which he keeps recorded in his "Book of Threats" or "Devil's Handbook", and uses this information to blackmail everyone from students to figures of authority into placing him in a position of power. He has little respect for authority and has in fact usurped authority over Deimon High School well before the series begins and know authority of a vice principal, using his power in the school to give himself beyond-perfect scores in all his classes and divert funds to the American football club as he desires. Besides blackmail, Hiruma can often intimidate others into taking the action he wants by waving around his vast arsenal of firearms. Even without having to take direct action, Hiruma's mere reputation is enough in some instances to make the majority of the student body fear him and bow to his authority.
Despite his penchant for blackmail and breaking seemingly every school rule without consequence, Hiruma adheres to the rules of American football without exception while playing. Inagaki says that Hiruma "does everything else to win" and is "only concerned with winning." Instead, Hiruma attempts to throw opposing teams off guard through taunts and insults. Even when Hiruma expresses excitement or happiness, he does so in a violent manner, by firing his large guns into the air or kicking a teammate in the rear when they have executed well on a play. He addresses all members of the Deimon Devil Bats with a vulgar manner, beginning with "Fucking" and ending with a descriptive noun, such as "Shorty" for Sena or "Monkey" for Monta. Some characters, such as Kid, have observed that Hiruma's attitude and even aspects of his demonic appearance are an act to intimidate his opponents both on and off the field. Over time, the series has alluded to Hiruma's 'true' personality, which Sena and Mamori Anezaki have at times been shown to understand to some degree, as when one or the other correctly observes Hiruma to be worried, happy, or tired. In addition to these instances, Hiruma has shown compassion to others, though he continues to hide it with his demonic behavior —allowing Takami some privacy after a loss is one such instance. In addition, some of Hiruma's actions imply that he cares for the other members of the team more than he lets on.
(Source: Wikipedia)
