Case Discussion
This case starts with a car driving through the railings and into the sea.
The driver was a robber, that died from the impact of the crash, due to him not wearing his seat-belt. His robber companion fled from the sinking car and is now hidden among the beach visitors. What they robbed was branded wristwatches, which they carried in at least one bag.
The only people that that bought beach shirts/sandals/shorts(in order to blend in with the others) right after the accident was these three suspects...
Fukumizu(the fat guy) claims to have been pushed into the water by his angry girlfriend, as they were sitting on a rubber boat. His wallet was on the rubber boat and safely avoided water damage, so he used it to buy a T-shirt and shorts. The rubber boat was abandoned on water.
Kitamori(the woman) claims to have been swimming and that her sandel's strap tore off, so she decided to buy new ones. She only came with her wallet, and have been keeping it in a locker while swimming. The old sandals were thrown away.
Ooami(the slim guy) claims that his bag with his clothes were stolen as he was showering, and only his wallet, which he hid between the towels, where left. So he bought a Hawaiian shirt for 300 yen. He was wearing two wristwatches and claimed that it was a part of his pick-up routine.
Yukiko asked Yusaku for help and he realized immediately who the robber companion was, just by looking at their appearances through a sent photo...
- Fukumizu wears a T-shirt, shorts and a wristwatch on his left wrist, while carrying his wet clothes with his left arm.
- Kitamori wears a wet swimming/beach outfit and a wristwatch on her left wrist, while holding her wallet with her left hand(The first panel seems to have a drawing error).
- Ooami wears only his trunks and the Hawaiian shirt, while wearing two wristwatches(with different timezones) for both wrists.
So how did Yusaku realize who the culprit was?
The first thing he would notice is their clothes. Yusaku is already expecting that the robber bought new beach-wear to blend in, but the robber would have avoided carrying the clothes that they had on during the robbery, since it could be identified by the shop workers that were involved, later on. This eliminates Fukumizu, who was carrying his wet clothes.
Kitamori wasn't carrying her wet clothes, however she was holding her wallet. If her wallet was drenched with water, it would prove that her wallet was recently in contact with the water, possibly due to the accident, so the robber wouldn't have had the wallet on them. Fukumizu wasn't holding his wallet, however, since he has shorts on, he is most likely keeping it in his pocket.
The only suspect left is Ooami, who has neither a wallet or wet clothes with him.
Another thing that Yusaku might have noticed is their wristwatches. Normally, people usually wear their watches on their non-dominant wrist.
Fukumizu wears his watch on his left wrist, which means, he should be right-handed. Sure enough, the fact that he is carrying his wet clothes on his left side indicates that he really is right-handed, since people usually leave their dominant hand open for action.
The same goes for Kitamori, who wears her watch on her left wrist and also holding her wallet with her left-hand, so that she can use her dominant right-hand for actions like taking out money from her wallet.
That leaves us again with Ooami, who is wearing his branded watches on both wrists.
One of his watches seems to be a Sterling silver type, which could get ruined/corroded when in contact with the saltwater of the beach. For someone who's seemingly trying to show off his two branded watches(from Yusaku's perspective), he doesn't seem to know much about them. So, the true reason to why he is wearing two of them could be because he might not know on which wrist people normally wear their watch, since he doesn't actually wear watches himself, which is why he decided to go with the excuse of having two for different time-zones(since he was pointing with his right hand, he is probably right-handed and therefore should have worn it on his left wrist). So, since he has two valuable watches when he doesn't normally wear watches, Yusaku might've already figured out that they were stolen during the robbery.
So in conclusion,
the culprit is Ooami...!
The fact that Ooami had sandals and a swimming trunk on could mean that he was actually prepared for the "accident", meaning that it wasn't an accident at all.
Here's what could have happened:
- Ooami prepared his swimming trunks beforehand and brought his sandals with him.
- he and his robber companion stole the watches and put them in two bags.
- they drove off in a rush, but only Ooami put on his seat-belt.
- Ooami then forced the steering wheel so that the car crashed and went through the railings(killing off the only person who knew about the robbers' identity).
- After getting out of the water, with only one bag full of watches and his sandals, he then took off all of his clothes and put them inside the bag, along with the watches, and took out his sandals.
- To have an excuse to why he came to the beach, he decided to wear one of the stolen watches(ofc after removing the price-tag) as a"show-off" material, but after getting confused about which wrist people commonly wear them on, he decided to wear two instead.
- After taking out 300 yen coins, He then hid the bag with the watches, wet clothes and wallet, and bought the Hawaiian shirt.
Plot Discussion
File 972 starts with the flashback to 10 years ago, where we get the second(and last) official confirmation that Haneda Shuukichi is the middle brother of the Akai family. Akai mentions that it has been 7 years since he and Kichi met. Since Akai mentioned in File 948 that his father was the reason he joined the FBI, and that his father was involved in the "Haneda Kouji case" 17 years ago(from current time), it was already assumed that Akai probably trained to become an agent and therefore lost a bit of contact with his family in Japan.
Then comes the most adorable scene where Masumi apparently meets Akai for the first time, following by the the second(and last) official confirmation that Mary(the shrunken adult) is the mother of the Akai family. The interaction between Mary and Akai is basically exposition, further clarifying what most fans already deduced, until we get to the new vital information about what is known about the Akai father's(Mr. Akai's) incident...
We find out that Mr. Akai was the one that instructed the family to move to Japan and that he also left a message saying that the family should treat him as non-existent, since he made enemies with some really "horrible people". Akai then goes to say that his body was never found.
This info sheds some new light into the "Kouji/Asaca/Rum" mystery...
Let's go through the known Akai family activities in the timeline up until now:
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The Akai family lived in the UK before 17 yrs ago.
Akai mentions a home country(that isn't the US), and Mary's choice of of words already revealed to Yukiko that their mother is british, which in turn implies that Akai's home country is the UK. This means that Mr. Akai, Mary, Shuukichi and Akai Shuichi lived there. Since James Black, who's also british, is most likely the close friend of Mr. Akai, it makes sense that James' possible british tie to Mary could have lead to Mr. Akai meeting and eventually marrying her. Whether Mr. Akai lived in the UK the whole time or not is yet to be confirmed.

Shuukichi's shogi interest might be due to the influence of his Japanese father, since he most likely looked up to Haneda Kouji while Kouji was still alive(before 17 years ago, when he lived in the UK). Shuukichi's will to take on Kouji's surname, and also the fact that he quoted something Kouji said, later on, is probably an indication that they have at least met once in the past.
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The Whole family were in the US during Kouji's case 17 years ago
This would be the time where 10-11 year-old Shuukichi could've met Kouji, and where 12-13 year-old Akai's will to avenge his father sparked. By that time, Mary already got pregnant(could be an early pregnancy stage). However, the initial reason for the Akai family to fly to the US is still unknown. Reason to why they went there could be:
1. James(FBI) asked for Mr. Akai or Mary's help. Since Amanda Hughes, who was looking for a bodyguard at that time, had ties to the FBI/CIA, it's possible that she asked James to get her a bodyguard, and thus ending up with Mr. Akai/Mary who went with the name "Asaka".
2. Shuukichi, who wanted to meet Haneda Kouji, who was staying in a hotel in the US for a competition at that time.
3. Because the father is a CIA-agent who worked in the US, and was only occasionally visiting his family in the UK. Therefore, Akai and the rest of the family wanted to visit him this time....
Or...it could be a combination of all/some of these "reasons".
After, or during, Kouji's and Amanda's death, Mr. Akai disappears. Since Akai mentioned that a body wasn't found, it leaves reasons to believe that traces of Mr. Akai was left that implied a potential death, like blood(or body part). His message to Mary however, implies that he survived and is hiding from the "new" enemies, which we can already assume is the BO.
An interesting thing to note is that Mr. Akai referred to the BO as "horrible people", as if Mary or Mr. Akai himself didn't know about the BO's existence. Mary, who is assumed to be Elena's sister and possibly an MI6-agent, and who was probably involved in Elena's plan to "leave"(most likely a year before 17 years ago), should know about the BO. This could mean one of these three possible explanations:
1. Mary never told Mr. Akai about the BO and the Elena incident and/or her being an MI6-agent.
2. Mr. Akai doesn't know about the BO.
3. Mr. Akai didn't know that the "horrible people" were the BO at that time.
This implication does at least prove that Mary and Mr. Akai weren't involved in the same case together.
After being instructed to flee to Japan, they moved to Japan, but Akai decided to go back to the US for "educational purposes"(to become an FBI-agent and find out the truth behind his father's incident). The Akai family in Japan have now become the "Sera Family".
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The Akai/Sera family(+Masumi, -Mr. Akai) reunite 10 yrs ago(now), and Shuukichi later meets Yumi
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Akai infiltrates the BO in Japan, Masumi is in middle school, Shuukichi pursues the way of Shogi, while Mary is keeping a low profile, 5 years ago.
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Masumi and Mary moves to the UK and Shuukichi stayed behind, 3 years ago
The reason is most likely Masumi's encounter with the BO members Rye(Akai), Scotch and Bourbon, 4 years ago. Mary probably feared that it was too risky to have Masumi stay in Japan any longer, now that some BO members saw Rye's sister and Akai is climbing up the BO ladder.
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Akai's infiltration ends, 2 years ago
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Current time, Masumi(Sera) returns to Japan with Shrunken Mary, Shuukichi is a meijin, Akai is disguised as Subaru
The reason for Sera and Mary's return to Japan is probably the fact that Mary was forced with the Apotoxin 4869 drug and shrank. The reason to that she became a target could be:
1. She is the bodyguard of Amanda, "Asaka", and she was being hunted by Rum, who was responsible for Kouji and Amanda's death.
2. She is a former spy that infiltrated the BO at least 18 yrs ago.
3. Her relation to Elena, a former BO researcher, is the reason they targeted her(to erase any living connections to the dead).
Shiho, Mary's niece, who created that drug, is the only one who could help her.
Sera's reason, for joining her mother's trip(besides helping her out), is Shinichi/Conan, who as many suspected, was seen on TV in Wimbledon. Since he called himself "Holmes' apprentice" in File 972, it's pretty obvious at this point that Sera and Mary saw him during the london case, when he called for Minerva(Tennis player) and said that he is "Holmes' apprentice"(since Sera said that she used to watch sports with her mother in File 876).


The big question now is...
where is Mr. Akai?
The first suspicious person, that got introduced in this arc is Kuroda Hyoue. Because of his fishy coma-backstory, it leaves the possibility, for a swap taking place, open. In this case, Mr. Akai could have taken Kuroda's place, while the real one is still in a coma(or perhaps even dead). That would of course need the help and approval of the NPA(Kuroda's former Agency), unless he had the help of other parties(CIA/BO) to switch in secret.
Mr. Akai could've been "Asaka"(bodyguard), who because of some feminine features(like his hair), was mistaken for a woman, But that doesn't give an answer to his current whereabouts.
The more darker route is still a possibility, where Mr. Akai was Rum all along, and his disappearance was just a facade in order to leave his family and focus on the BO mission, but it's still a crazy alternative.
A fourth possibility is that he hasn't appeared yet, but eventually will...
...or it could be a combination of all/some of the alternatives.