Unknown if anyone stated this before....
But Anyhow With my constant random thoughts about, Whats Sera's connection to the BO?
I remembering reading the Gosho interview posted on the forums.
The contents of the interview... said something about Sera and Ai being like wolves (Correct me If I am wrong).
I thought about the term Vermouth and the other members referred To Conan and Akai as "sliver bullets". What is said to kill wolves-------> Silver bullets. I think Sera has some type of connection to the BO.... Maybe like Ai, Former member, Family was part of the BO. So adding to her possibly being Akai's sister. (I know that was already stated).... hmm...
Anyhow Why did Carmen recognized/ thought Sera Looked familiar. When he been working behind a desk, ever since he unknowingly revealed to the BO who Akai really was (Mentioned in the Clash of the RED/Black Episodes {I believe}).... Also Carmen felt it was important enough to mention it to Jodie and James....etc.
Akai wouldn't have left his sister without protection, he is not like Kir. Its strange, James knew Sera was a girl, It seems too easy. I Hate cliffhangers!!! That's why she isn't in the next Manga case.