This is almost certainly bullshit. When the U.S. Government seizes something, it's public knowledge. There are court documents. There's usually a press release. There are public lists of seized items. The FBI can't put a "gag order" on a French citizen in Japan anyway.
i ll be there to quote you on this when we have more details of what really happened.
You should look a bit into history and who were the losers of WW2 and how there are over 50k US troops in various military bases all around japan. How many military bases does japan have in the US?
Does that not ring "occupation" within you?
Another good example is Germany.
If not the FBI, there is also the NSA and CIA, and the CIA has been operating for quite some time now in various nations.
If you think the US cannot control the Japanese gov in various ways, i have a bridge to sell to you.