Hetalia: In Secret And Shadow (MiB AU)

"You'll conform to the identity we give you, eat where we tell you, live where we tell you. From now on, you'll have no identifying marks of any kind. You will not stand out in any way. Your entire image is crafted to leave no lasting memory with anyone you encounter. You are a rumor, recognizable only as deja vu and dismissed just as quickly. You don't exist; you were never even born. Anonymity is your name. Silence, your native tongue. You are no longer part of 'the system.' You are above the system. Over it. Beyond it. We're 'them.' We're 'they.'

"We are the Men in Black." - Agent Zed

Since the 2010 Pictonian Invasion of Earth, the MiB has been working around the clock trying to clear the memory of it from all humans. While returning from a containment effort, Agent A, a familiar wheat blond teen with his tell-tale cowlick, runs into a friend from work. Alfred Jones is left scrambling about in a desperate attempt to keep his work in the agency a secret, fully aware of the panic it could cause. However, Ivan Braginsky is determined to uncover the truth and figure out what it is that Alfred is hiding, no matter the cost.

Looks like the MiB has their work cut out for them.