The Hong Kong Kowloon Treasure Murder Case File 1 - S1-E1
Plot hole: The plot of the four-parter is complete nonsense even for a kid show. It is tied together by unbelievable pure coincidences; Miyuki is the perfect doppelganger of a missing model, Kindaichi randomly bumps into a high school mate who just happened to be in HK as well (!), and they both equally randomly (so they think) bump into the model who was just chilling on a park bench (so much for disappearing!), he befriends the son of the victim from 20 years before.
The Hong Kong Kowloon Treasure Murder Case File 2 - S1-E2
Plot hole: An essential part of the plot relies on the fact that thanks to Saki's handheld camera, Kindaichi can examine Ran's arse dragon and therefore investigate even in her absence. But what set the plot in motion was the fact that Ran appeared in a professional modelling photoshoot displaying it. Stupidity of the girl aside, that means that the culprit never needed the girl, having HQ shots of the tattoo at their disposal. They even work for the company.
The Hong Kong Kowloon Treasure Murder Case File 3 - S1-E3
Plot hole: The surprise reveal of the killer doesn't make any sense, because Kindaichi gathered everyone involved in the case, and the killer very much is; they are absent for no reason, so the denouement shouldn't have even started and the audience would have to be napping not to notice.
The Hong Kong Kowloon Treasure Murder Case File 4 - S1-E4
Plot hole: Miyuki has been peacefully waiting for over a day at a stranger's house because she was told that the whole Hong Kong was under lockdown and her friends were in another location. That cover story (which would have been exposed if only she looked out of the window, people were NOT in lockdown) does not explain at all the kidnapping in the clothing stall or why she didn't have her phone or talk to Hajime at any point. She'd have to be braindead not to question even slightly what was happening.
The Hong Kong Kowloon Treasure Murder Case File 4 - S1-E4
Plot hole: The plot involves mother and daughter having a matching tattoo on their butt. This episode tells us that they had the matching tattoo since Ran was literally a child since her father himself did it. It's easy to understand that since kids, you know, grow and all, a dragon on the buttock of a 6 years-old would be quite different when they are all grown up. And it's no small tattoo and it needs to be accurate because it's a map.
The Alchemy Murder Case File 3 - S1-E8
Plot hole: The locked room mystery is original, but besides the fact that it requires melting part of a door on the spot and being able to repair it absolutely flawlessly so that nobody would notice any bump and discolouring and irregularity when they check the lock later investigating the murder, it also requires them to do it in total silence so the other guests don't notice, and part of the process shown involved cutting through it with a screwdriver and bashing it with a hammer - they show that and there's even a loud sound effect for it. (00:18:00)
The Alchemy Murder Case File 4 - S1-E9
Plot hole: The ending is funny, but it does not make sense, since as it was mentioned in the first episode, there was literally 1 ton of metal to remove, and it was in the shape of a door. Not only it would have needed 32 trips (as the nerd girl says in the first episode) from the secluded house to a large boat they somehow needed to have standing by and was undetected when the island was searched earlier, but they also needed to dismantle the door, since that's what the gold was turned into.
The Prison Prep School Murder Case File 3 - S1-E12
Plot hole: Kujiragi's textbook is missing. It's a plot point and it's something the culprit did to plant an evidence using a page from it. However, when the case is solved, this point is glossed over; only a page from the book was needed, which the culprit could have ripped away at any moment without stealing the book, and more importantly, when Kindaichi finds the book, there was no window of opportunity for the killer to put it back; Kindaichi and Kujiragi were right there in the corridor the whole time. The live version adaptation fixes this hole because the character finds his book only the day after, in class.
The Prison Prep School Murder Case File 4 - S1-E13
Plot hole: The basic causality principle is reversed when explaining the murder with the corpse discovered on fire. The lesson was about combustion and took place before (or during, rather) the murder, so it couldn't be something used to disguise an unexpected problem that hadn't surfaced yet. Additionally, there's no reason why the murderer couldn't act as first responder or place the body near the river or in the bathroom.
The Prison Prep School Murder Case File 5 - S1-E14
Plot hole: The victim managed to write a dying message with chalk on the inside of the locker, but the only moment when he could have done that was when his assassin was standing there watching him die waiting to drag his corpse away. Since the writing was basically the killer's name, it's absurd that the killer never bothered to wipe out the signs; it's chalk on hard metal, not a single trace would have remained. It also does not match the position of his hand in the second episode.
Inspector Kenmochi the Murderer File 2 - S1-E20
Plot hole: One of the plot points of the episode lies in the fact that Kenmochi is accused to be the killer because only the cops had Busujima's phone number, apart from his two accomplices. That point holds absolutely no weight; the killer is a killer because he, well, killed someone, and that someone was exactly one of those accomplices. It's a fact that can't be ignored by even the most ignorant investigator, especially with the accomplice's phone being directly involved in the murder. (00:10:15)
Inspector Kenmochi the Murderer File 2 - S1-E20
Plot hole: The brief intermission when Busujima meets the 'killer', or at least the person wearing the hat, does not make sense plot-wise and is merely a dishonest way to trick the audience. It's not even something Busujima tells someone, so it can't be characterized as a 'unreliable narrator' device. (00:18:30)
The Game Mansion Murder Case File 3 - S1-E25
Plot hole: An additional plot twist of the episode has the Puppeteer from the Hell as the mastermind behind the operation. What does not make sense is the fact that he regularly visited the killer in prison showing his face fully in the open. To make it even more ludicrous, the next episode shows that he needs to constantly wear a mask because he's wanted by the police, and he is on the run. Previous episodes showed already without a doubt that the police had all his data and pictures.
