Those are Consular Reports of Birth of United States Citizens Abroad. Unless citizenship derives through the legal principle of jus soli even on overseas military bases, he wouldn't have one. A quick google search seems to indicate that birth on overseas military bases does not enable a jus soli claim to citizenship, meaning he is limited to a jus sanguinus claim, which he has already indicated he was not eligible for.
I've just been all over the Tachikawa City homepage, and I must be getting stupid, because I can't find an address for the city office on there anywhere.