The History behind the Devil

Before the clock ticked the first time

Several years before the series timeline, when Hiruma was still a ten-years-old grade-school kid, he snuk inside an American military base through a hole in the fance surrounding it. His attention was soon caught by the American football match that they were helding, immidiatly realizing just how much that game was based on strategy and intelligence.
Hiruma's freely roaming in the American base, however, didn't last long as he was found by one of the soldiers which treatened to send him to jail (probably he was tring to scare him off, cosidering how Hiruma was still just a kid). The little devil however didn't lose his composure one bit and just quickly made up an excuse to him being in the base. When the soldier realized it was just a lie, he was amused by that strange kid's behavior and decided to show him around, not fully understanding just who he'd to do with. In a short time Hiruma ended up learning poker and winning most of their money out of the other soldiers in the base.
Since that day Hiruma regularly went to the American base to bet on American football matches.

The first tick of the clock

At some point when he was in middle school, Hiruma meets Ryoukan Kurita who tries to recruit him for the American football club after seeing by chance some of the gameplays that Hiruma'd drawed up. Although at the beginning he refuses to join Kurita, not interested at all in playing the game iteself, he changes his mind after they're forced to partecipate in one of the soldiers' games after two of the regular members had collapsed from heatstroke. As the team Hiruma's betted on actually lose in the end, he's now detemined to play the game and reach the Christmas Bowl.

As both Kurita and Hiruma want to create an American footbal club, the vice-principal at their school is against it, so Hiruma gets the idea that "in order to make an American football club they have no choice but to start by making something else" which, in this case, means a threat notebook. He then creates a massive network of information to acquire blackmailing material by virtually everyone in Tokyo also thanks to his temporary alliance with Agon Kongo.
After threating the vice-principal (with a quite amusing S&M pic of him), Hiruma and Kurita are finally able to re-form the club with Doburoku Sakaki as club advisor. Later, when the latter points out that a club ought to be formed by at least three members, they try to persuade Gen "Musashi" Takekura into joining them. At the beginning the other boy isn't really willing to do so, having to help his father with his job, but then decides otherwise when he starts to think that the two "seem like fun".

When they finished middle school, Hiruma, Kurita and Musashi decide to enter Shinryuuji High to join their football team, but, realizing that Kurita couldn't possibly pass the written entrance exam, Hiruma signs him up for the sports merit program to allow him to join the team. However Agon, thinking the three of them being "trashes", applies for the program as well, spoiling Kurita's opportunity to enter the school.
Hiruma and Musashi decide then that rather than leaving Kurita, they'd enter another school (Deimon High) with him, creating again a new American football club and team, the Deimon Devil Bats. Nobody however seems to want to join the club (to the point that Hiruma is forced to coerce members from the other sport clubs to fill up their team during matches) and eventually Musashi is forced to leave the team to help his family business when his father falls ill.

When the clock runs wild

The actual story of the series begins a year later, when Hiruma recruits Sena Kobayakawa (with the usual forceful metods) as runningback for their team after he witnesses Sena's incredible running speed and agility. He then hides Sena's identity to prevent other clubs from trying to recruit him as well and gives him the nickname "Eyeshield 21", covering his face with a green eyeshield when they're having matches and giving him the jersey 21.
As they are soon beaten by the Oujou White Knights during the Spring Tournament, the only chance for Hiruma and Kurita to reach the Christmas Bowl becomes the Autumn Tournament (also because of Deimon policy of not allowing club activities to the third-year students).

During the series Hiruma takes the role of both strategist and coach (the latter until he don't bring back Doburoku from America), and his hellish training routine is resposible for the quick development of his team-mates, although he personally doesn't show any rilevant physical improvement. His weapons are his mind, his talent for trick plays and his almost amazing ability for taunting their opponents, but he does show a relavant change for what concerns his relationship with his team-mates: at the beginning he's basically very objective, then he slowly develops a kind of faith in them to the point that they even do some plays without having a huddle beforehand.
In the end the Deimon Devil Bats manages to partecipate to the Christmas Bowl against the Teikoku Alexanders and at the end of match, Hiruma gets to the point of completely discarding his objectiveness, putting his faith in his team-mates even when victory seemed statistically impossible, which ultimately leads to the Devil Bats winning the championship.

Following the Christmas Bowl, Hiruma goes on a short trip to USA to spy on their team in view of the World League and he's later selected as one of the two quarterbacks of Team Japan, and he later mentions the fact that he'd "struggle to death" to become the torunament MVP and join the NFL.

In chapter 333 (the last chapter of the series) the story is skipped two years ahead, showing Hiruma being part of the American fooball team of his college, Saikoyoudai.

An intersting fact that has to be mentioned is that in chapter 318 is revealed that Hiruma's father, Yuuya, was an amateur chess champion that has tried to move to the pros. However, he was forced to adopt a defensive style of chess due to his continous losing against them, and eventually completely gave up on it.