Whenever Hiruma wants somebody to do something for him, he pulls out his little black book full of black mail material which has information on seemingly everybody.
I know he started the book to get approval to start the American Football club but is it ever explained how or where he gets all this information? He seems to have dirt on pretty much everybody in Japan.
The information were gathered using hacked cameras, mostly in cellphones. The hacked network was that great, that he could get information of nearly anything in Tokyo, and he never stopped that network.
Funfact:
In one of Q&A column, it is revealed that the book was actually blank- All the information lies within Hiruma's brain, and the book only serves as a threat tool.
Source: Eyeshield 21 Wiki
