Well this is just a theory, though after thinking about the identity of Anokata, I realized something really interesting.
The FBI, CIA, M16, CSIS, BND, and PSB (And I'm guessing even more) are all involved in the case of the Black Organization. From this, we can understand many things, though I'll highlight possibly one that people might miss.
The Federal Bureau of Investigation is an American national security force focusing on domestic affairs. There would be no point in the FBI being stationed in Japan as they only focus on issues within America, foreign threats are dealt with by the CIA.
The M16 are a British national security force focusing on foreign affairs, while the M15 focus on domestic affairs.
Now the only reason the FBI would be involved is if the threat originated in America. The M16 being involved and not the M15 (They might still be involved, no evidence they aren't but likely not) prove that it wasn't just one security organization asking for help from others, since the M15 would also be involved (To an extent) as well.
I haven't thought more in depth of this but I'm sure it could help in finding whoever Anokata is. For instance, he'd might be someone who can speak English or he might be a foreigner (I heard he's confirmed Japanese so not sure on that though).
Any thoughts in the comments are appreciated. I didn't really think this through all that much; I might have missed something important.