Ezio wrote:
Putting the Pieces Together:
Sera works for an espionage-related organization and has exceptional skills in martial arts and deductive reasoning. Her skills in martial arts and deductive reasoning might have been obtained while she trained and worked for the organization. She is willing to have criminals killed (like she did with the bomber in file 773), probably due to the fact she witnessed countless deaths during her work in this organization. This organization is most likely the FBI, due to the fact that Sera lived in America recently (the FBI is an American organization) and has a possible connection to a "former" FBI agent (Akai). She moved to America 3 years before the current timeline; this was the same time in which Akai infiltrated the Black Organization, meaning that the reason for her move to America is probably related to this (perhaps she took the FBI's Witness Protection Program to stay safe from danger). She moved back to Japan to work on a case; this case is most likely investigating the "death" of her relative/comrade, Akai Shuuichi. She has detailed knowledge of the Japanese Police Force; she might have received this information from her fellow agents in Japan to prepare herself for her investigation. The reason for her investigation would probably be that she has suspicions surrounding the circumstances of his death (similar to how Jodie felt). This would also explain why she is investigating Conan; he is the second-last person to have contact with Akai before he died (the last being Rena Mizunashi/Kir) and is likely to have information on what went down.
Correction: Akai infiltrated the BO 5 years ago and was stood up two years ago, which means he spent 3 years as Moroboshi Dai.
I'd rather say that Sera has connections to the FBI but she isn't a member herself. I don't think Akai would have allowed her to join the FBI (I'm assuming they are siblings), but he was not against training her. I think she was trained well, in order to be able to protect herself.
I think Sera has a connection to Jodie, after all Jodie was Akai's girlfriend, so I can imagine that Jodie may have told Sera about the young, amazing kid, who helps them in their investigation.
Ezio wrote:
Sera is NOT Bourbon/Scar Akai
Assuming that Scar Akai is the recently-active Black Organization member Bourbon in disguise, it is impossible for Sera to be Bourbon. During the 13 red shirts case (Files 700-705), Bourbon/Scar Akai "borrows" a cell phone from a man in the department store, and then gives it back while asking him if it was his. When the man spoke to Ran and Conan afterwards, he identified Scar Akai as a male, meaning that Scar Akai likely has a deep or manly voice. It might be possible for Sera to change her voice in similar fashion to Vermouth, however, the fact that Scar Akai (almost) always kept his silence implies that he is not able to mimic voices. It would also be impossible for Sera to disguise as Akai, due to the difference in height and physique (Sera is around the same height as Ran, and Akai is almost a full head taller than Ran).
I'd like to point out that the bases of you theory that Sera cannot be Scar Akai is that you assume that Scar Akai is Bourbon. However that is just another theory, which is not proved yet.
The guy in the department store assumed that Scar Akai was a man, because of his looks, but even a girl can sound like a guy, such an amatuer as me too, to disguise her voice as a male voice for a short spoken sentence.
The only thing which is troubling me is the height-problem. :/ I don't know if it is possible to fake height so much. I still have hope though. ;)