Rum Arc Discussion Thread (Plot + Characters)

[Shinan-Kudogawa]

True, one on the edge of life. Being attacked, would naturally stab the attacker, leading to blood. However are we sure that the scissors were not stained with blood?, there is nothing known fully about that. Furthermore, the fact is, his attacker is more than likely a far skilled martial artist that Kouji. Which would mean that the attacker managed to be bruised rather than stabbed, at a split second.

The scissors are yet to be fully revealed, plus kouji was probably near sighted, which reinforce the chance that he missed.

True, we cannot be sure whether the scissor were not stained with blood except if it were yet the one at the crime scene were not then that brings a probability that RUM or the B.O. or whoever came after not managing to have time to do some clean up or tampering on the crime scene ~ that the crime scene was left as it were~ may be false. Let's assume that there were blood spilled and the scissor used by Kohji to attack the assaulter that was stained with blood was switched with one that was clean and a false "dying message" was set up instead by putting broken pieces of the mirror back into it's frame... then who would gain from such an act? A member of the B.O. or an enemy of the B.O. or someone else?

I'd restrict myself from going over board, and meanwhile guessing that who ever took a piece of evidence already took the scissors, for example Wakasa. While speculation on my end, is rather based on hypothesis. Suspicion naturally falls onto her, as she took the Shogi piece, which we believe was at the crime scene. She may have took with her the scissors, and a hand mirror (Soul Detective). You brought to my attention, a speculation of 'false' dying message. As in, someone planted the dying message to implicate BO??!. If that's the case, then it is someone who knew the BO are involved, and wanted to implicate them in the murder. Meaning that, whoever did it, tampered with the evidence to implicate BO/Asaka/Rum, would Wakasa implicate Asaka in the crime, if she is Asaka??!. I doubt it is the BO themselves made the evidence to implicate their personnel, and it is not their M.O. . Most likely it was either Wakasa, if she is not BO, or someone else entirely not belonging to BO.

[Zerozaki4869]

Just a little addendum,
How was Kohji able to make that message and leave the shogi piece as the dying message ?

Kohji had to flee, get back to his room, fetch the mirror and the scissors, made the message with real haste, then Rum came in had beaten the shit out of him, during the fiasco Kohji was able to cut the mirror without removing its backing, thrown off the scissors, picked up the piece and again picked up the scissors. It is too unrealistic.

I've seen people making a case that Kohji removed the backing of the mirror and after cutting the message he picked up all the glass shards and put them on the backing. Sounds ridiculous given the glass shard fragments sticking to the backing proving that it was not removed.

Some do say that Kohji was holding the shogi piece while making the message, which also is very unlikely and nobody can use their hands freely in that situation. So all in all the mirror message looks like not something done by Kohji.

[Shinan-Kudogawa]

Just a little addendum,
How was Kohji able to make that message and leave the shogi piece as the dying message ?

Kohji had to flee, get back to his room, fetch the mirror and the scissors, made the message with real haste, then Rum came in had beaten the shit out of him, during the fiasco Kohji was able to cut the mirror without removing its backing, thrown off the scissors, picked up the piece and again picked up the scissors. It is too unrealistic.

I've seen people making a case that Kohji removed the backing of the mirror and after cutting the message he picked up all the glass shards and put them on the backing. Sounds ridiculous given the glass shard fragments sticking to the backing proving that it was not removed.

Some do say that Kohji was holding the shogi piece while making the message, which also is very unlikely and nobody can use their hands freely in that situation. So all in all the mirror message looks like not something done by Kohji.

My guess would be either to agree with your statement, that someone else left the mirror. Or that Kouji did leave the mirror and the Shogi piece, however, whileso Rum was fighting someone else perhaps Asaka. Or vice versa, while Rum was fighting Kouji, someone else (maybe Asaka) left the messge before leaving, that is as long as Asaka is acting against Rum..

[Zerozaki4869]

Kuroda called Kansuke from a different number and also a different handset.
He even asked Kansuke to put the call to Morofushi, but................


This has happened earlier.
So Kuroda's phone call has two unanswered questions,
a) Why call Kansuke from a different number/handset ?
b) Why not call Morofushi directly ?

The result of Kuroda's action has two consequences though,
Morofushi now is not in a position to save the number.
There is no tangible proof that the person who called them was actually Hoye Kuroda, if this other number is registered to a different persona/name.

[Zerozaki4869]

These are my updated theories
a) Wakita theory
b) Rumi theory
c) Kuroda theory

[Unlucky Devil]

These are my updated theories
a) Wakita theory
b) Rumi theory
c) Kuroda theory

They certainly seem like very promising theories. If I may add one point, which may or may not have been mentioned earlier. When Kuroda calls Kansuke, he calls from a white phone, when he is looking up Wakasa Rumi, it is on a black phone, which in several instances in the past has been proved to be a sign of someone affiliated with the BO, albeiit under cover (like Shuichi was shown with both coloured phones)

[Nemomon]

In another topic I wrote this:

Anyway, I'm still not sure who's Rum. If not Rumi, then it must be Wakita. It probably can't be Hyoue because of the meeting Kuroda had with Rumi during the camping. If we assume that Rumi is Asaka or anybody else that was near or during the murder of Kouji, and then Kuroda is Rum, then he most likely would recognize Rumi (well, actually both of them recognized each other) as one of the murder witnesses, and he would try to kill Rumi. But he didn't even try considering that Rumi still is working in the school. On the other hand, if Kuroda is Tsutomu, he should not know Rumi at all, and vice versa, because Tsutomu appeared after the murder and after Asaka fled, and therefore they would not recognize each other. Therefore Kuroda cannot be Tsutomu nor Rum if Rumi is Asaka.

Therefore I still think that Rumi is Rum. She chose that fake name because she wants to lure people who would react to "Rum". Also, it also could be that Rum met Kouji before they murdered him. If Rumi is Rum, it also would explain the reaction of Rumi when she met Kuroda (Rum-i knows Kuroda is Tsutomu, and that's why they acted hosstile to each other. But Rum-i has also another mission, so she could not try to kill Kuroda back then, and Kuroda didn't do anything to Rumi, because he's not a killer).

===

Therefore I think that:

Rum - Rumi
Asaka - Wakita
Tsutomu - Kuroda

Why Rumi is Rum I explained above. Why Wakita is Asaka? Wakita says bad things about Rum, if Wakita would be Tsutomu, he could not even know who's Rum. But if Wakita is Asaka, he would firsthand see how Rum screwed their job, and that's why he says that Rum is not the best of horses out there. And since all other positions are already taken, Kuroda must be Tsutomu.

[DCUniverseAficionado]

In another topic I wrote this:

Anyway, I'm still not sure who's Rum. If not Rumi, then it must be Wakita.

Kanenori Wakita being Rum would be as surprising as Tōru Amuro being Bourbon—even less so, in fact, considering this is coming right after the Bourbon arc. If that's the route Goshō's going for, his main objective isn't surprising us—rather, it would be in what comes after the reveal (i.e., how Team Shinichi/Conan will deal with the situation). Same applies if Rumi turns out to be Rum.

Therefore I still think that Rumi is Rum. She chose that fake name because she wants to lure people who would react to "Rum". Also, it also could be that Rum met Kouji before they murdered him. If Rumi is Rum, it also would explain the reaction of Rumi when she met Kuroda (Rum-i knows Kuroda is Tsutomu, and that's why they acted hosstile to each other. But Rum-i has also another mission, so she could not try to kill Kuroda back then, and Kuroda didn't do anything to Rumi, because he's not a killer).

To me, there's no point in Goshō showing us how unstable and violent Rumi is unless there's a subversion/twist coming—it singles her out way too much (that and her remembering Kōji's watchtower bishop quote, calling him a fool, and clutching her eye—it makes her look quite guilty).

Spoiler:

And now, in 1,052, we even have Rei/Bourbon concluding that Kōji's killer must be at the farm, because only his killer would have the shogi piece. This is more of Goshō going, "See, look! She is so suspicious!"

It probably can't be Hyoue because of the meeting Kuroda had with Rumi during the camping. If we assume that Rumi is Asaka or anybody else that was near or during the murder of Kouji, and then Kuroda is Rum, then he most likely would recognize Rumi (well, actually both of them recognized each other) as one of the murder witnesses, and he would try to kill Rumi. But he didn't even try considering that Rumi still is working in the school. On the other hand, if Kuroda is Tsutomu, he should not know Rumi at all, and vice versa, because Tsutomu appeared after the murder and after Asaka fled, and therefore they would not recognize each other. Therefore Kuroda cannot be Tsutomu nor Rum if Rumi is Asaka.

Why Wakita is Asaka? Wakita says bad things about Rum, if Wakita would be Tsutomu, he could not even know who's Rum. But if Wakita is Asaka, he would firsthand see how Rum screwed their job, and that's why he says that Rum is not the best of horses out there. And since all other positions are already taken, Kuroda must be Tsutomu.

In regards to Hyōe... that panel of him recalling Kōji's body and then connecting it to Rumi is either going to convict him or exonerate him for me.

He's the only one who does not recall a pool of blood beneath Kōji's face (when Mary, Rei, Shinichi/Conan, Yumi—and Rumi, of all people—either think of or mention the case, they all recall a pool of blood beneath Kōjis face). That seems to imply Hyōe saw Kōji before he started bleeding from the mouth, which also seems to imply he was there at the scene, at or around the time of the crime—that certainly doesn't look good, in terms of his culpability.

On the other hand, rather than recognizing Rumi, he could be connecting Kōji's head turned to the side to the golfer culprit that Rumi knocked out, and that his head was turned to the side in the same fashion. That would imply that Hyōe is not the culprit, but an investigator who suspects Rumi of being the culprit of Kōji's murder (assuming she put Kōji on the ground the same way she took down the golfer culprit). If this is indeed what Hyōe's thought process was, then the likelihood of Kanenori being Rum increases.

And in any case, Tsutomu didn't get involved in the case until the murders had been committed, so Hyōe being present at the scene (whether Hyōe is Rum or not) points to the idea that Hyōe is not Tsutomu (barring either: (1) a huge Tsutomu = Rum curveball from Gosho, which, imo, isn't a complete impossibility... but it has a very, very low possibility of actually happening, or (2) a reveal that Tsutomu actually was involved with the case from the start). With Tsutomu having the presence he's had during this arc, I was convinced one of the male Rum suspects was actually him. At this stage, I'm thinking he's either Kanenori, still hiding and hasn't yet appeared, or is truly dead.

Because Muga and Rumi both have long hair, I'd be less surprised if one of them turns out to be Asaka. Hyōe or Kanenori (especially Kanenori) turning out to be Asaka? In terms of physical appearances, that'd certainly be unexpected. Given the ASACA RUM message (even after it's been revealed to actually be CARASUMA), I'm inclined to think Asaka isn't really Rum. If Hyōe isn't Rum, and isn't Tsutomu, then I can see him being Asaka. Kanenori being Asaka (or any other 3rd party, really) is now a distant possibility for me. I used to be more open to the possibility that he was a BO member who wasn't Rum, but at this point, I'm of the idea that he's either Tsutomu or he's Rum.

So, for me, at this stage...

Stance I'm confident in:
Rumi ≠ Rum

As for the rest...

If Goshō isn't going for a surprise:
Rumi = Rum

If Goshō really isn't going for a surprise:
Kanenori = Rum

If Hyōe = Asaka and Asaka ≠ Rum:
Kanenori = Rum

If Kanenori ≠ Tsutomu:
Kanenori = Rum

If Kanenori = Tsutomu:
Hyōe = Rum

[Zerozaki4869]

TBF, if we plot capabilities of the three Rum suspects we'll be pleasantly surprised.

Kuroda despite having knowledge of Police work for a long time, he struggles a bit. During Camping ground case he overlooked the skewers and the candle.

Rumi despite of having no knowledge about Forensic work, she knew the exact time and situation of decomposition of a deadbody.

Wakita during the Mountain Villa in Snowy Mountains case immediately tested the Water for cyanide by using his own copper coin.

So in a nutshell we see more Forensic awareness from Rumi and Wakita and less experience in Police work from Kuroda.
As of now no characters who aren't inherently detectives hasn't shown this prowess.
As of now Kuroda hasn't shown anything remarkable about his Forensic knowledge.

[lulwa]

About Rum , I have been thinking about it , and I think Sera Masumi is Rum , their seem to be many hints by Gosho about Sera being a wife when he said about movie 24 the akai family and the wife plus when haibara says that Taiko could have put marriage form for Yumi Sera calls Conan saying she is now in the hydo pride hotel > pride > bride , and if we take into consideration that lum is the second "waifo" ever and the fact that both Sera and lum have vang like tooth plus Sera is shown to dress a lot in strips the same as lum.


Another thing , in Sera's first appearance , she told Ran your just my type of rival that is , and lum has a rival named Ran .


Gosho was asked could a code name be inherited or something like that he said , I can't say .


In the message sent to bourbon by Rum he tells him'
Time is money" just like the way Sera uses English language "case closed".


Gosho said Sera is the most important character since haibara , and that both of them are sharks ,could mean both of them from the same org ?


In the chapter where shinichi and Ran go to the aquarium if we see that aqua rium > aqi rum > Aki Rum
Plus shinichi was waring red while standing in front of the sharks .
And in the end Ran asks shinichi for the sea cucumber stap , the one that Gosho shows in a Sera appearance also ,and the love rivival could mean love rival ?


Also I've noticed that when ever Sera appears their is a mention to eyes or see or sea .




Could that be possible?

[BrickBreak]

No.

[blackmoon]

About Rum , I have been thinking about it , and I think Sera Masumi is Rum , their seem to be many hints by Gosho about Sera being a wife when he said about movie 24 the akai family and the wife plus when haibara says that Taiko could have put marriage form for Yumi Sera calls Conan saying she is now in the hydo pride hotel > pride > bride , and if we take into consideration that lum is the second "waifo" ever and the fact that both Sera and lum have vang like tooth plus Sera is shown to dress a lot in strips the same as lum...
Could that be possible?

Hahaha... that is the funniest Rum theory I've heard so far! Sera being RUM is just.... like saying Kohji Haneda isn't actually dead and is actually Rum and the corpse of Kohji that was found was just a fake.
And i actually thought about that possibility until someone asked Gosho in an interview and he confirmed that Kohji isn't Rum... and neither is Kansuke Yamato.

Because Muga and Rumi both have long hair, I'd be less surprised if one of them turns out to be Asaka. Hyōe or Kanenori (especially Kanenori) turning out to be Asaka? In terms of physical appearances, that'd certainly be unexpected. Given the ASACA RUM message (even after it's been revealed to actually be CARASUMA), I'm inclined to think Asaka isn't really Rum. If Hyōe isn't Rum, and isn't Tsutomu, then I can see him being Asaka. Kanenori being Asaka (or any other 3rd party, really) is now a distant possibility for me. I used to be more open to the possibility that he was a BO member who wasn't Rum, but at this point, I'm of the idea that he's either Tsutomu or he's Rum.

If we must include having long hair being a possibility for Rum's 'female' aspect then... Morofushi may be suspicious as well as he quoted a Chinese proverb equivalent of "Time is money, as the saying goes."
And for what reason did he quoted that in front of Bourbon and Wakita?

[Cognac]

If we must include having long hair being a possibility for Rum's 'female' aspect then... Morofushi may be suspicious as well as he quoted a Chinese proverb equivalent of "Time is money, as the saying goes."
And for what reason did he quoted that in front of Bourbon and Wakita?

I could only think of two probabilities atm:
1) Wakita = Rum. Amuro/Bourbon (and probably most BO members) has never seen Rum, so he does not or cannot recognize Rum in person. Asked by Hyoe, Morofushi appeared there to warn Amuro about Wakita being Rum. In this scenario, then Morofushi and Hyoe are good guys.
2) Hyoe = Rum. He asked Morofushi to deliver Rum’s message to Amuro/Bourbon, with making sure that it doesn’t sound obvious to Kogoro and Wakita. In this scenario, I am not sure whether Morofushi is aware that Hyoe is Rum or not, so I cannot yet conclude which side he belongs to. He could be another BO member, or just a police officer doing a favor/task asked by (seemingly) another police officer.

[Mohamed Ebrahem]

Hello everyone, I am Mohamed from Egypt .
This is almost my first post on your blog. Iam very happy to know you and read most of your conclusions in this discussion on Arc Rum. You are great.
What made me write this post is that I found you still do not know who is rum yet, but some of you really expect his identity as we expect and for that I will tell you our logical conclusions and we are sure of it : Rum is definitely Chikara Katsuma and he's the same Karasuma , reasons :
1- He appeared in the next chapter as soon as Kir announced that Rum would appear, and this is a style of Goshu known to show very important characters at the beginning of the Arcs .
2- shogi player like Haneda Koji, the case of the arc of Haneda Koji death was mentioned by Haibara in the second appearance of Chikara Katsumata , with whom he sings the title of the Migin in the Shogi Game, his presence at the hotel where Haneda Koji is expected as a shogi player too, strong, much like Goshu in the outward appearance hahaha , He looks very similar also to Karasuma when he was fifty and looks like a crow too , but Goshu does not show this in all panels so not to attract the attention of fans , the panel page 10 file 899 .
3- Chikara is impatient, as Amoru hinted to conan, and this obvious on Chikara's face while he waits for the coming of Haneda Shukichi. Haneda Shukichi also told the Detective boys that the shogi world is impatient in page 8 file 900 .
4- Itakura killer , is some one called Suma and he was a software engineer for shogi games. He said that he and Itakura were aiming to make the best shogi program to defeat the Maigens, and this may be the program that the black organization was interested in , That means a member of the organization is a shogi player and will definitely be a chikara .
5- one of both eyes is an artificial and you will notice that difference between them if you look carefully . And he appeared on key hole with different eyes also of the Folder 85 .
6- He did not has an identification card that tells us his name and age, Chikara himself said his name and this is very doubtful because his age is very very large considering that he is a Karasuma and therefore it will be confusing to fans if someone appears in his card has 140 years for example .
7- In the cover of Chapter 906, Conan poss is very similar to the Chikara poss .
8- Whenever Chikara appears , the Akai family appears. This is evidence that there will be a Close association between Chikara and this family , Even when Chikara appeared in the file in background, the Akai family also appeared in the same file in the background in file 1043 .
9- There is an important thing that most of the fans did not notice, and it is the inspector who appeared in The Magician of the Waves series files 972 973 974 , this inspector is very similar to Chikara and he will be himself and the inspector also did not show an identification card for him in his name and age just like a Chikara , This is logicl because , RUM had a military background, just as Sebastian Moran . Of course in this case , Tsutomu Akai family was present throughout this series ,Mary calling Akai by shuichi in front of Chikara .
10- The image of Yumi that fell from Haneda's pocket is most likely taken by Chikara, which means that Yumi, perhaps at time of the confrontation, will be in danger as it is the first case in which Chikara appeared and in that case Yumi kidnapping occurred , perhaps this is a hint from Goshu .
11- Agasa cheats in his puzzle at the beginning of Arc Rum. This was a hint from Goshu that he was going to trick us this time , chikara resembles the fourth paper dish completely devoid of skull shape but the cup on it contains vinegar inside , so Chikara in front of us in the Arc not doing any suspicious behavior Unlike the other three suspects .
12- Hotel where Haneda Kohji died is called juke so there is also a second trick or cheat in the arc , Haneda Koji's real message , and Goshu hinted that the name of the hotel on the cup that fell on the mirror, which led to the mirror broken down compeletely not because of a specific person . so Haneda Koji had not any relation with the mirror message .
13- The real Haneda Koji message, which Haneda himself did , was holding the shogi piece horse uma in his palm and was hidden by holding scissors tightly , this shogi piece after death of Kohji was taken by Wakasa so that the organization did not destroy that evidence , Wakasa made the hand mirror clue (Karasuma) , She also seems to know him well because she talk about him and his traits in file 1051 , and this increases the possibility that she is Asaka a former BO agent . but the dying message of Kohji was only holding scissors tightly and uma shogi piece :
tightly = power which is mean chikara
scissors means katta + uma shogi piece
collect all of those terms in Japanese you will get ( Chikara Katsumata ).
14- Wakasa was very smart , She took two pieces of shogi with her. ( the favorite piece of koji from his pocket as he always holds it so she wanted to keep it Which fell from her pocket and picked up by the Amuro at file 1051 chicken farm case ) , and took also ( the uma piece from his palm ) so that the BO could not destroy the real dying message , but she left an important guide/clue/evidence for smart investigators instead of the uma piece which she took with her , If we look at the hand mirror that left next to Haneda's corpse , Wakasa had scratched (u) letter of the word (put) on the shape of shogi piece , so that investigators conclude that the missing shogi piece that missed from Haneda's palm is started with (u) and it was definitely the uma piece which she had taken that important evidence as we mentioned for not to be destroyed by BO .

[Conan4869]

Hello everyone, I am Mohamed from Egypt .
This is almost my first post on your blog. Iam very happy to know you and read most of your conclusions in this discussion on Arc Rum. You are great.
What made me write this post is that I found you still do not know who is rum yet, but some of you really expect his identity as we expect and for that I will tell you our logical conclusions and we are sure of it : Rum is definitely Chikara Katsuma and he's the same Karasuma , reasons :
1- He appeared in the next chapter as soon as Kir announced that Rum would appear, and this is a style of Goshu known to show very important characters at the beginning of the Arcs .
2- shogi player like Haneda Koji, the case of the arc of Haneda Koji death was mentioned by Haibara in the second appearance of Chikara Katsumata , with whom he sings the title of the Migin in the Shogi Game, his presence at the hotel where Haneda Koji is expected as a shogi player too, strong, much like Goshu in the outward appearance hahaha , He looks very similar also to Karasuma when he was fifty and looks like a crow too , but Goshu does not show this in all panels so not to attract the attention of fans , the panel page 10 file 899 .
3- Chikara is impatient, as Amoru hinted to conan, and this obvious on Chikara's face while he waits for the coming of Haneda Shukichi. Haneda Shukichi also told the Detective boys that the shogi world is impatient in page 8 file 900 .
4- Itakura killer , is some one called Suma and he was a software engineer for shogi games. He said that he and Itakura were aiming to make the best shogi program to defeat the Maigens, and this may be the program that the black organization was interested in , That means a member of the organization is a shogi player and will definitely be a chikara .
5- one of both eyes is an artificial and you will notice that difference between them if you look carefully . And he appeared on key hole with different eyes also of the Folder 85 .
6- He did not has an identification card that tells us his name and age, Chikara himself said his name and this is very doubtful because his age is very very large considering that he is a Karasuma and therefore it will be confusing to fans if someone appears in his card has 140 years for example .
7- In the cover of Chapter 906, Conan poss is very similar to the Chikara poss .
8- Whenever Chikara appears , the Akai family appears. This is evidence that there will be a Close association between Chikara and this family , Even when Chikara appeared in the file in background, the Akai family also appeared in the same file in the background in file 1043 .
9- There is an important thing that most of the fans did not notice, and it is the inspector who appeared in The Magician of the Waves series files 972 973 974 , this inspector is very similar to Chikara and he will be himself and the inspector also did not show an identification card for him in his name and age just like a Chikara , This is logicl because , RUM had a military background, just as Sebastian Moran . Of course in this case , Tsutomu Akai family was present throughout this series ,Mary calling Akai by shuichi in front of Chikara .
10- The image of Yumi that fell from Haneda's pocket is most likely taken by Chikara, which means that Yumi, perhaps at time of the confrontation, will be in danger as it is the first case in which Chikara appeared and in that case Yumi kidnapping occurred , perhaps this is a hint from Goshu .
11- Agasa cheats in his puzzle at the beginning of Arc Rum. This was a hint from Goshu that he was going to trick us this time , chikara resembles the fourth paper dish completely devoid of skull shape but the cup on it contains vinegar inside , so Chikara in front of us in the Arc not doing any suspicious behavior Unlike the other three suspects .
12- Hotel where Haneda Kohji died is called juke so there is also a second trick or cheat in the arc , Haneda Koji's real message , and Goshu hinted that the name of the hotel on the cup that fell on the mirror, which led to the mirror broken down compeletely not because of a specific person . so Haneda Koji had not any relation with the mirror message .
13- The real Haneda Koji message, which Haneda himself did , was holding the shogi piece horse uma in his palm and was hidden by holding scissors tightly , this shogi piece after death of Kohji was taken by Wakasa so that the organization did not destroy that evidence , Wakasa made the hand mirror clue (Karasuma) , She also seems to know him well because she talk about him and his traits in file 1051 , and this increases the possibility that she is Asaka a former BO agent . but the dying message of Kohji was only holding scissors tightly and uma shogi piece :
tightly = power which is mean chikara
scissors means katta + uma shogi piece
collect all of those terms in Japanese you will get ( Chikara Katsumata ).
14- Wakasa was very smart , She took two pieces of shogi with her. the favorite piece of koji from his pocket of and took the uma piece from his palm so that the BO could not destroy the real dying message , but she left an important guide/clue/evidence for smart investigators instead of the uma piece which she took with her , If we look at the hand mirror that left next to Haneda's corpse , Wakasa had scratched (u) letter of the word (put) on the shape of shogi piece , so that investigators conclude that the missing shogi piece that missed from Haneda's palm is started with (u) and it was definitely the uma piece which she had taken that important evidence as we mentioned for not to be destroyed by BO .

This is the best Rum theory I have ever heard and I % agree with it..only minor doubt that you are thinking itakura was developing shogi software which I am not sure of since Rum's idea conception was quite late in the series and it cannot be that Gosho had already thought of Katsumata so early on...rest all I think you are highly accurate