Theory: New character Sera Masumi Is An FBI Agent

[Ezio]

As many of you may have noticed, a whole lot of clues about Sera's identity have been given throughout the past four chapters (Files 768-771). If you put the clues together, an interesting possibility emerges: Sera is an FBI agent. The following are the steps I took to arrive at this conclusion along with facts and evidence to support them:

Sera Works For an Espionage-Related Organization

In File 769, Sera suggests that she has sharp ears "due to her line of work" (pg 2), suggesting that she works for an organization that involves stealth and information gathering. She also suggests that she has witnessed "innumerable" jumper suicide scenes (pg 3), suggesting that the organization she works for also involves dealing with homicide cases.

Sera Has Detailed Knowledge of the Japanese Police Force

In File 773, just by noticing a flickering light outside the Detective Agency windows, Sera recognizes the presence of the police, the number and name of their units, their tactical positions, and their plan to defeat the bomber in a very short amount of time. She also goes as far as to help them in their plan by luring the bomber to the window to allow the snipers to shoot him (much like how a normal police officer would act). The source of her knowledge and expertise is unknown.

Sera is Highly Skilled in Martial Arts and Deductive Reasoning

Sera displayed her skill in martial arts in File 768 when she counter-attacked Ran (who is an exceptional martial artist herself). She displayed her deductive abilities in File 769 when she deduced that the jumper-suicide was actually a homicide disguised as a suicide.  

Sera is a Japanese-American That Moved Back to Japan Recently

In File 771, Sera tells her classmates that she moved back to Japan after living in the United States with her parents for a period of 3 years (pg 2). Apparently, the reason for her return to Japan is that it is "easier to be a detective", suggesting that she is working on some sort of case.

Sera Has a Possible Connection to "Deceased" FBI Agent Akai Shuuichi

In File 771, when scolded for his actions in the previous case by Haibara, Conan says that Sera is "not an enemy" because she resembles someone he met before (pg 11). Conan has previously worked with Akai during the Clash of the Red and Black. Sera physically resembles Akai (compare the two faces, especially the eyes) who is also a Japanese-American. Also, as some people have mentioned, the name "Sera Masumi" is very similar to the name "Sayla Mass" (Seira Masu), who is Char Aznable's younger sister in the Gundam Wing anime franchise (Akai is named after Char Aznable himself). Also, Sera mentioned that she moved to America three years before the current timeline; this was around the same time when Akai infiltrated the Black Organization as "Morobashi Dai".

Sera is Investigating Conan

Interestingly, Sera seems to know Conan's name as well as the fact that he is a "detective" despite it being their first time meeting each other. She also knew Ran as well as Professor Agasa (file 771). The source of this information is unclear, however, Haibara points out that Conan's name has come up in newspapers due to his battles with Kaito Kid. She also goes as far as to purposely get her deduction wrong in order to let Conan solve the case himself, probably to test his deductive abilities. In File 771, she shows extreme interest in meeting Conan face-to-face, and alludes to the fact that Conan is the "brain" behind Kogorou's deductions. In File 773, she hints to Ran about the connection between Conan and Shinichi, possibly meaning that she knows or suspects Conan's identity. The reason and motive behind her investigation are unclear, however, it is possible that she is investigating Conan because he had contact with Akai shortly before he "died".

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.

COUNTER-THEORIES:

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).

"Sera is Too Young to be An FBI Agent" - Sera's True Age Has Not Been Revealed

Many of you have been arguing that Sera might be too young to be part of such a high-level organization. However, even though Sera showed up in Ran's class as a high school student, her true age (as well as her identity) has not been confirmed; assuming that she's an FBI agent, she could have forged the papers necessary to register for school, which would allow her to act as a high school student. I would also like to mention that Jodie Starling (a current FBI agent) is around 28-29 years old, and has been a member for at least 5 years (it was shown in flashbacks that she was a member during Akai's time in the Black Organization), making it possible for a young woman such as Sera to join as well. Although Sera commented that her breasts could "pop out any day", a woman who is 17-years-old would have already completed her sexual and physical development. This lie might have been told to give people the impression that she is younger.

Sera is NOT a Black Organization Member

Some of you have mentioned that Sera could also be a member of the Black Organization. This theory is not very likely, due to the fact that Sera publicly worked with the police to solve a case (Files 768-770). If Sera was called in for questioning by the police, her identity as well as her involvement in the organization would have been exposed. If she was a BO agent, she would have a certain cover/identity; this identity can easily be exposed if she was questioned and interrogated by the police (for example, if she was a BO agent and an undercover high school student, the police can expose her identity by revealing her true age). This is out of character for the organization, as they would avoid contact with law enforcement during their work (similar to how Gin and Vodka acted in the first chapter of the series).

"What if Sera's identity as an FBI agent was exposed?" - Easily Excusable

If Sera is an FBI agent and came to Japan to work on a mission, her identity could be exposed. However, this is not an issue because Sera can make an excuse for her stay in Japan such as visiting a relative, vacation from work, or going back to high school to finish her education. Jodie and Camel did the same thing when they were uncovered by Takagi and Megure during the Clash of the Red and Black (File 606).

I hope you enjoy my theory, and please feel free to leave comments and/or counter-theories to prove me wrong.

[Silver1412]

I thought about it too. However I'm not really sure. Isn't she a little too young? ~nya!

[James Rye]

How about she´s a member of the BO?

When Shiho was around her age she already gained her code name so unlike the CIA or FBI Sera wouldn´t be too young to enter their organisations.

Also you can see what you brought as clues/facts the other way aorund as well.

Stealth and information gathering is something the BO does as well. Witnessed "innumerable" jumper suicide scenes can mean, that she knows how to fake suicide deaths cause she was often part of such murders. Skilled Martial Artist can also be a clue that she´s part of the BO, who ever said that BO agents can only shot and stab?
About Conan and his instincts, remember the Bus bomb case where he told Haibara that he felt that there was no one who wanted to kill her while she was afraid the whole time cause a BO member was on board? Truth was that there was someone who wanted to see her dead, Sharon hidden in Araide disguise. He either simply lied to Haibara or didn´t knew about that fact till then which makes more sense.
Same here, he had met Sera for a short time and she´s already suspicious cause she knows his name and seems to be alot interested into his opinion considering murder despite him being a child. Conan may be a good detective but he has no BO-radar like Haibara. He could have met her earlier in America where he had also met Sharon who was a friend of his mom and turned out to be a BO agent, a high ranked one even.
Unlike Eisuke who believed first that Kogoru had some infos considerng his sis, Sera ignores Kogoru as she already knows that he´s not that good as the newspaper says. Getting infos outta newspaper of TV news is something BO does too. Remember when Conan feared once he was shown in a tomorrow TV show cuase 10% in Japan watch that show? When Agasa got confused why Conan was so worried about that, he told him that there´s no guarantee that not a BO member saw that show. Same can be here with Sera who investigates the possibility of Shinichi becoming Conan. Who says that not till now someone else got poisoned by APTX but turned into a child right before the BOs eyes?
Sera cannot be a FBI agent in my opinion cause first FBi don´t let kids in and second FBi is as you say an America organisation which fights crimes in America. James Black and his people are only in japan cause of the BO which did alot of crimes in theri country and they believe the boss of them to be here. However they are hide from both the japan as well as the american goverment or better the media. What do you think will happen once it´s known that FBI agents are running around in japan, fighting crimes, shooting around, getting targeted by bombs from the BO, etc.? For the CIA that´s normal though still a tabu to get found out, so Kir and her father makes sense with her BO infiltrating but the FBI is over-stepping their lines of work, meaning they would only let few people know about this operation which excludes family members of those participating. The less know the less can talk.
As third oposing argument, they would never let a family member of a killed agent become a new part of an already existing operation team. The risk that this person gets driven by emotions and does something stupid is too high. Heck, even Jodie is already a risk to the team and she got years of training.
So Sera being a FBI agent is out of question for me, it´s even more likely that she´s a BO agent, but considering Gosho and his *Conan was always and will always be right*-strategy Sera will turn out to be some good person who fights crime and especially the BO.

[Silver1412]

M<aybe she was shrunked but few years ago! ~nya!

[thorongil]

i like the first theory much better because i already like sera quite much... but i won't disregard the contrapoints... at the moment both are quite possible and most of the things we know about her can serve as evidence for each theory... although i don't believe she is an agent of any kind...
you shouldn't forget what sonoko teased ran about just before she appeared... maybe that was a hint about her upcoming role?... idontknow...  (dont like this myself)..
I just hope that we don't have to wait too long to get to know about her intentions...

[Stopwatch]

Hmm... some parts make sense but there are a few holes you'll have to figure a way round. I'll just point out some flaws:
1) Like Silver1412 said, it seems unlikely Sera is old enough to be an FBI agent (though this also lowers the chance of her being Bourbon)
2) What reason would she have to investigate the death? The FBI in Japan may not have permission to be there but I doubt they'd keep it a secret that someone (i.e. Akai) died. Normally relatives and people like boyfriends/girlfriends are the first to be told about stuff like that. Only thing I can think of at the moment to explain something like that is rather farfetched:
-Sera or Shuichi got entered into the Witness Protection Program (I'll shorten this to WPP in following sentences) - This explains why their names are different.
-They somehow kept in contact without being allowed to - This bit would means that when Akai stopped contacting Sera ('cause he was going into hiding / he stupidly forgot to write it down before his phone got broken) Sera would have reason to investigate. After all if one of them had gone into the WPP then they weren't supposed to keep in contact in any way at all, the FBI wouldn't imform Sera of Akai's death because 'Sera Masumi' and 'Shuichi Akai' aren't related (if you get what I'm saying  ;))
3) How would she know that Conan was around Akai shortly before his 'death'? that would imply that she had contact with the FBI in Japan, but if that happened then she would also know the details of Akai's death and so would also know that Akai was sorta shot through the head! And that his body was Confirmed Dead by Fingerprints! Why would she investigate when all evidence (that she could find out from the FBI in Japan) points towards Akai being DEAD

...just noticed that three other people have posted while I was rambling on, gotta say I agree with James Rye on quite a lot of points
Anyway, lets see if you can counter these flaws...  ;)

[Silver1412]

thorongil is right... But are you aqlways so straight to the point? ~nya! Hard to believe you're younger then me. We're crazy here! ~nya!
And I agree with you Stopwatch, but call me Silver or Agatha ~nya!

[bluekaitou1412]

I like the Sayla Mass reason

She's a BO member masquerading as Akai's sister :V

[Silver1412]

And here we have have bluekaitou...  Wouldn't she say her last name is Akai then? ~nya!

[Commi-Ninja]

I like the Sayla Mass reason

She's a BO member masquerading as Akai's sister :V

Yeeesss....

And here we have have bluekaitou...  Wouldn't she say her last name is Akai then? ~nya!

Unless they're half-siblings, or she changed her last name for some other reason.

[Silver1412]

I like the Sayla Mass reason

She's a BO member masquerading as Akai's sister :V

Yeeesss....

And here we have have bluekaitou...  Wouldn't she say her last name is Akai then? ~nya!

Unless they're half-siblings, or she changed her last name for some other reason.

But she didn't said she was Akai's sister so we can't say she's pretending to be one! ~nya!
Be reasonable guys! ~nya!              This coming from me...

[bluekaitou1412]

Of course, she wasn't exactly flat-out pretending to be Akai's sister, she might be just borrowing her face for cover though.

[Silver1412]

Who ever said Akai hada sister? Wait! Why am I being reasonable? She's pretending to be Akai's sister ~nya!

[bluekaitou1412]

Akai mentioned his sister a while ago iirc. This Sera character must've been just plotting around with Akai's sis' face, then when confronted she can have an excuse. "I'm Akai's sister! Obviously I'm innocent :V"

[Silver1412]

He did... I didn't know ~nya...