Ron Kamonohashi: Deranged Detective (鴨乃橋ロンの禁断推理, Kamonohashi Ron no Kindan Suiri, sometimes also called Ron Kamonohashi's Forbidden Deductions, which is a more literal translation) is a manga that began its Shonen Jump debut on 10th October 2020, and is written and illustrated Akira Amano of Reborn! (2004) fame.
Officer Totomaru Isshiki is down on his luck. The police department has been stuck on a serial murder case for months, and, due to his constant screw-ups, he is in danger of being taken out of the Investigation team altogether. He is then introduced to Ron Kamonohashi, a private detective who might be able to help solve the serial murder case and allow Toto to remain on the team.
However, Kamonohashi has a "fatal flaw" that makes him "unfit" to be a detective, and, as a result, he's not accepting any more investigative work. It's up to Toto to help him with his issues to convince Ron to get involved in the case, and perhaps help the supposed Great Detective return to his work.
The series has many references to Sherlock Holmes, with Ron and Totomaru corresponding to Holmes and Watson, respectively.
In December of 2022, it was announced
that the manga would receive an anime adaptation. It would be produced by Diomedea and was released on October 2, 2023. A second season was announced which will air in October 2024.
The series provides examples of:
- Animal Theme Naming: All of Blue's instructors introduced so far have animal related names: Spitz Feier the tracking instructor, John Grizzly the "closed circle" instructor, Fin Fennec, the locked room studies instructor, and Dr. Hirsch (German for "deer"), the anatomy instructor.
- This also applies to the students that have been introduced so far: Ron Kamonohashi (Japanese for "platypus"note ), Shachi (Japanese for "orca"), and Elmer Stingray.
- Aside from that, there's also Kawasemi (which means 'Kingfisher'), whose trademark pincer habit seems to be taken from his namesake's beak, which alleviates its own hunting by effectively 'slicing' through the water and picking out fish. note
- Arc Symbol: Chapter 3 establishes that Ron's strangely-shaped scar has mysterious origins from an incident and chapter 13 reveals the symbol's relevance to the plot as it was inflicted on him during the Bloody Field Trip incident five years ago and it appears again during the Island Observatory Murder, indicating several connections between the two as the symbol has only appeared during times, he was being set up to appear as a murderer. It's meant to be the number 96, representing Ron being both the ninth generation descendant of James Moriarty and the sixth generation descendant of Sherlock Holmes.
- Batman Gambit:
- The Island Observatorium Murder Case had its main death hinging on this: the killer left Onodera dazed but awake in the telescope room, with all the lights destroyed and the door glued shut. Predictably, once she awoke, she went towards the light switch and the door, which had emergency lights, when she couldn't open the door, she assumed it was locked, and turned the lock, locking it instead. Then, the killer predicted she would look for the other lightsource, the telescope switch, and turn it to try to get the light of the sky and help, and that was the trigger for the trap.
- The Poisoned Latte Case hinges on the killer having an intimate knowledge of the victim's social media habits. The victim, Julie, was always posting photos of herself and tried to always make it the best possible. To make sure she'd pick the poisoned cup, the killer messed up the latte art of the other two cups, knowing her friend would pick the only one that still looked good and drink it, so that was the one she poisoned.
- Breather Episode: The Case of the Missing Cabbage has all the characters come together to celebrate Isshiki's birthday and the only source of trouble comes about because they don't have any cabbages to put in the hot pot they're eating for the party. Though characters speculate that the lack of cabbage at every grocery store in the area could be because of more violent crimes, it turns out that Spitz just bought them because he doesn't like cabbage. Ultimately, it's a light interlude for the characters to goof off and have fun between the various murder cases that comprise this series.
- Bunny-Ears Lawyer: Is Ron even a detective? note . Like Sherlock Holmes upon whom he was modeled, Ron definitely qualifies as a Bunny-Ears Lawyer. He is addicted to brown sugar (to the point of including it in everything he consumes), lies down and talks to the corpse every time he arrives on the crime scene, has an endless amount of zany disguises and aliases that barely qualify as aliases, and is a serious Lazy Bum. He's a Cloud Cuckoo Lander every chance he gets, apparently for his own entertainment. This apparently improves his thinking processes.
- Catchphrase: Ron's 'I'll avenge you' to just about any corpse he encounters on any crime scene. He also lies down next to it if possible when he says that.
- Chekhov's Gag: In chapter 3, Amamiya barges into the men's bath in a hot spring and accidentally flashes Kamonohashi and Isshiki when thinking she's at the women's bath. This turns out to be a clue as the killer had changed the signs of the baths so he could set up a trap to kill his wife in the feminine one.
- Chekhov's Gun: As typical of murder mysteries.
- In chapter 1, Ron deduces that Toto was at a shrine due to having pine pollen on his shoulder and noting he was taught to not walk through the center of the shrine path. This fact is what allows Ron to overcome the Sadistic Choice of either shooting Toto dead or allowing a room of civilians to die by using a trick with shadows to imitate a tori gate to non-verbally tell Toto to lean away as far as possible to only graze his shoulder.
- In chapter 2, Isshiki is left with the task of solving a case of a woman who thinks someone stole from her piggy bank when he tries to offer to participate in a murder case headed by Amamiya. In the end, Kamonohashi reveals that the two cases are connected when the murder victim turns out to have been killed using the piggy bank.
- In Chapter 5, Yamane confirms that the man they tried to arrest the night prior had a tiny bird tattoo on his forearm. Then the protagonists notice that being dark, he shouldn't be able to notice said tattoo unless he got close to them, which is when he would be cutting his hands.
- Closed Circle: The Observatorium party turns into this when a murder occurs, of which Ron is the main suspect, and nobody can leave, nor can the cops get to them due to a massive storm happening around the island.
- Death Faked for You: The Jim Gore case turns out to actually been a plan by Eliot to protect Gore, a brilliant pathologist, from being exploited by the M Family. The body thought to have been him was a dummy for a morgue while the real Gore escaped to Switzerland under a fake name.
- Defective Detective: Ron is a Cloud Cuckoo Lander, a brown sugar addict, and in great mental pain. Investigating run-off-the-mill cases is beneath him. It takes Totomaru quite some effort to get him to help him.
- Didn't See That Coming: Milo is clearly caught off guard when Ron gets around the Sadistic Choice of either fatally shooting Toto or releasing a nerve gas that would kill everyone in the room by using a trick of the shadows to get Toto to lean as far as possible thanks to a hole in the door that Elmer helped create earlier.
- Drop Dead Gorgeous: In the third case, a naked woman is found drowned in a supposedly cursed hot springs. The corpse receives more focus in the anime adaptation than in the manga, and appears less covered in leaves while still avoiding explicit nudity.
- Evolving Credits: The opening of the anime's first cour features a brief sequence of Toto and Ron walking through the city past various out-of-focus figures. As the season progressed, these figures were gradually replaced with in-focus characters from completed cases.
- Fake Mystery: Ron and Toto visit the Blue Academy to investigate a case, and pretend to be teachers while they are there. After his first day of teaching, Toto is called by some of his students, who report that one of their friends is missing, only to find the girl dead in a locked room. The whole incident turns out to be a prank set by the students to scare their new teacher. Toto (actually Ron) managing to solve the case wins his students' respect.
- First-Name Basis: Soon after they meet, Kamonohashi starts being this with Isshiki, whom he calls simply Toto, and asks to be called simply "Ron".
- Freudian Excuse Is No Excuse: Zigzagged. Hummingbird's reason for serial kidnappings is that his daughter's failing health and broken mental state causes her to only react to artistic geniuses; he kidnaps them and makes them interact with his daughter in order to try to aid her recovery. Isshiki calls him out that despite this, his actions are still criminal, and he put his latest would-be victim under extreme stress. Ron, however, is much more forgiving, and lets him go despite Isshiki's desire to arrest him, noticing that after each kidnapping, not only was Hummingbird's daughter happier, but so were even the kidnapping victims who found the experience with his daughter somewhat therapeutical and started putting out masterpieces after talking with her. While Isshiki insists a crime is a crime, Ron seems happy with the largely positive outcome of them, though he mostly seems to want to face off against Hummingbird's brains again.
- Genius Ditz: Mofu Usaki, a witness for the Live Broadcast murder, is so extremely clumsy, she's constantly covered in bandages. One would be forgiven for not believing she's a genius neurosurgeon at first glance.
- Hero with Bad Publicity: Ron Kamonohashi himself is this after his fall from grace; being the only survivor on the scene of a Locked Room Mystery that baffled a school staffed by the world’s best detectives will do that. His mysterious “condition” only worsened his reputation over the next few years, as he himself acknowledges that a detective that (inadvertently) killed culprits isn’t worthy of the title. Even after the truth behind the original murder is revealed and Ron officially graduates from Blue, his reputation still isn’t fixed. The upcoming generation of detectives already believed that he was working for the M Family, and they simply started thinking that he was so dangerous that he was able to infiltrate Blue all over again.
- The Return to Blue arc gives Isshiki a turn at being this. It turns out that the students of Blue think that Ron orchestrated the events of the Observatory arc, and the Blue instructor Grizzly was killed protecting Isshiki. This solidified their hate for Ron, but they also blame Isshiki for letting the crime occur. The students’ distrust of Isshiki leads to them heading out on their own even though the school is sealed off and two people have already died.
- Improvised Weapon: A piggy bank. A woman uses it as a bludgeon to kill a stalker invading her house when she is cornered by him.
- Killing in Self-Defense: In chapter 2, a woman kills a stalker targeting her and her sister when he tries to invade her house using her sister's full piggy bank.
- Locked Room Mystery: Chapter 9 introduces not only the Locked Room Instructor of the Blue Academy, but also a mystery of the sort when a murder occurs in a locked observatory, and when the door is open, only a passed-out Ron and a dead girl are found.
- Phony Psychic: The Live Broadcast case revolves around a television one that murders someone on live television and claims to have murdered the victim with psychic powers to escape being tried for it.
- Psychic-Assisted Suicide: This is essentially what Ron's fatal flaw is about - anytime he's pinned down someone as the murderer and that person has confessed, he'll pressure them into killing themselves via a compelling voice; notably, he lacks any memories of doing this every time. He does eventually get a little better thanks to medicine from Usaki; which also has side effects of him re-experiencing childhood memories. This also inadvertedly helps him solving what really went down during the Bloody Field Trip. In the end, he cut out his vocal chords in order to suppress this ability; when he gets them back, he is supposedly cured.
- Public Domain Canon Welding: The protagonist is a descendant of both Sherlock Holmes and James Moriarty. The "M" side of his family are set up to be antagonists.
- Public Domain Character: Sherlock Holmes and James Moriarty take part in the story: Ron seems to be the inheritor of both men, being the sixth Holmes's lineage and the 9th in Moriarty's. The M Family, the most powerful crime family in all of the world are implied to be the Moriarty family, and therefore Ron's distant relatives.
- Recurring Element: Amano seems fond of making her MCs be wimpy, uncertain young male characters with boyish charm. Isshiki continues this trend from Tsuna of Reborn and Chuuta from elDLIVE, who were younger versions of this trope.
- Serial Killer:
- Chapter 1 starts with a series of strange killings of men that had their valuables stolen and were found drowned, though they were all on dry land. The culprit turns out to have been a barber that killed certain clients to steal from them by making them pass out using oxygen-deficient air and drown themselves in the shampoo sink.
- Chapter 5 has the investigation revolve around a gruesome serial killer that cuts off and steals the hands of their victims. The victim of the case turns out to be that very serial killer who had his own hands taken.
- Sherlock Homage: Even though he starts out without taking any cases anymore and he's not actually allowed to solve cases, Ron does eventually return to solving mysteries. Ron also has the snark, the genius, the addiction (albeit to brown sugar), and a nice Heterosexual Life-Partner. Bonus points for Ron's blood being half of Holmes' lineage.
- Til Murder Do Us Part: In chapter 4, a man is revealed to have killed his wife in order to be with his mistress, who is disgusted with him for doing it.
- Whodunit: The manga follows multiple murder investigations, often of weird murders like people being drowned in dry land or a woman being murdered in a supposedly cursed hot springs, with the titular character trying to solve them and their mysteries.
