Conan tranquilizes Sonoko and begins his deduction. He says the murder weapon has not been found because it changed shape and turned into something totally normal after achieving its purpose. On hearing this, Takagi deduces that Tamai is the murderer, because he has an insulated container where a huge ice cube can be stored (later, the ice melts and the murder weapon is gone). Conan tells Takagi that he is wrong, because the chunk of ice is bound to break apart after repeatedly hitting a person’s head, but there is no sign of ice cube fragments in Moniwa’s room nor is there anything watery. Megure also gives his opinion: he deduces that the murder weapon must be Arimoto’s bottle of soft drink; Arimoto just needs the content of the bottle to be frozen in order to have an effective weapon. Conan rejects this conjecture as well; he says that if the content of the bottle had been frozen, then a long time would have been needed for it to melt completely, which would render it impossible for there to be no solid at all in the bottle during the belonging inspection. The true murder weapon, Conan reveals, is coins; more precisely, a large number of coins piled on each other in a sock (sock is, for some reason, known as “black jack”, which is also the name for a card game). Conan says that he is able to think of this by noting a subtle change: in the time period between the murderer (Kyota Honma)’s accidential entry into Conan’s room and the present, his left boot abnormally enlarged, meaning that he had put on an extra sock on his left foot (the police ususally do not check boots and therefore will not discover a blood-tainted sock). As for the coins, Honma could get rid of them easily by buying things in the vending machine. In this particular case, Honma bought a large quantity of cigarettes, as one of his personal belongings is a huge pack in which there are numerous cigarette cases. Conan explains that he definitely did not buy the pack as a whole (this is what Honma claimed) because all the cigarette cases inside the pack would then have the same production date; this is not the case. Another piece of evidence is that Honma once said to the police “even if I have met the victim, which I have not, it must have been in the corridor or in the bathroom (and definitely not in Moniwa’s room)”. Since Moniwa’s given name (Tatsumi, 巽 in native form) is used by people of both genders, and the bathrooms of the karaoke box are separated according to gender, Honma’s words suggest that he personally knew the victim. However, he told the police that he did not.
Honma, unable to explain why he lied on several occasions and knowing that the police are about to search for fingerprints on the coins in the vending machine, becomes aware that he has been completely exposed. He thus angrily admits that he does know the victim, as he was the kidnapper of his son, and killed the 4-year-old boy when Honma contacted the police. Megure says that he remembers the case that Honma is talking about: the police found out that Moniwa was behind it, but had to drop the charges due to a lack of evidence. Honma remarks that there was no evidence because the police failed to notice Moniwa’s trick (but he eventually did, and used it to kill Moniwa).
With the case solved, three highschoolers and Conan go back home. On the way, Eisuke remarks excitedly that he is impressed by Sonoko’s deduction; Ran agrees, saying that her performance was as good as Shinichi’s. Eisuke therefore asks whether they are talking about Shinichi Kudo, and Sonoko immediately affirms, and adds jokingly that Shinichi is Ran’s husband, but is not currently living with her due to a complicated case. Ran blushes and objects to the characterization as usual, and Conan changes the subject by saying that he wants to head back to the bookstore before returning home. Eisuke follows him, explaining to Ran and Sonoko that he wants to ensure that Conan is safe.
Conan sees right through Eisuke’s pretense and asks him what he wants to discuss in private. Eisuke thus informs him that he has decided to go to the United States. Conan asks whether that is because he accepted the FBI's witness protection program, and Eisuke replies that he rejected the program (Conan is anticipating this answer, as he knows that acceptance would mean that he would almost certainly never see Eisuke again), and that the Black Organization probably did not notice him. Eisuke continues to say that the real reason behind this decision is his dream to become a CIA agent and further his father and elder sister’s work. Conan comments (without saying anything out loud) that unless Eisuke fixes his carelessness problem the CIA will not employ him (at this very same moment Eisuke slams his chin on a utility pole); and he enquires curiously why Eisuke would bother to come back to Teitan High School if he is to leave soon. Eisuke answers that he is thinking of confessing to Ran during his brief return; he recounts that he fell in love with Ran at first sight, as he had never known a girl as gentle as she is. Eisuke carries on by saying that the problem is that Ran seems to like Shinichi; given this, he wants Conan to contact Shinichi to ask him whether he is fine with him confessing. Eisuke vows that if he is with Ran, he will never abandon her (unlike Shinichi), and will instead take her with him to the United States and give her happiness. Upon hearing this, Conan says solemnly that Eisuke cannot (confess); the latter responds that he is asking for Shinichi’s opinion, not Conan’s. Conan thus reiterates his objection to Eisuke’s confession.
Eisuke thus realizes that Conan and Shinichi are one. To Conan’s surprise, Eisuke is not surprised by this fact, but instead laughs out loud. Eisuke explains that since he initially thought that Rena Mitsunashi and Kogoro Mouri were “bad guys” who had colluded and hidden his elder sister, he did some research on Kogoro, and found that his deductive abilities always underwent a dramatic change after entering “sleeping Kogoro state”. Further research told him that Conan always appeared alongside sleeping Kogoro, and that the rise of sleeping Kogoro roughly coincided with Shinichi no longer attending school. In other words, Eisuke knew who Conan was from the beginning (but he does not know why Shinichi shrank into a child, nor does he seem interested in this matter). Eisuke also claims that he dropped a hint to Conan to imply that he knew his real identity (Conan overlooked this completely); specifically, during his first visit to the Agency, Eisuke deliberately bumped into Conan and, with his eyes closed, greeted Conan by saying “Hello, Detective Mouri…”.
Conan now realizes that everything that Eisuke has said a moment ago was part of a well-designed plot to force him to reveal the truth. Eisuke agrees, but says that his feelings towards Ran are genuine, and that he wants Conan to make her happy. Eisuke then mentions that something seems to have happened to the FBI; Conan acts as if he knew nothing about this, and Eisuke does not insist on asking. In the last panel, Conan thinks to himself (with a confident smile on his face) that something did happen, but that everything will be fine.