Recap / The Kindaichi Case Files Ayase Serial Murder Case

"Ayase Serial Murder Case" is the sixth case arc in the "The (37-year-old) Kindaichi Case Files" spin-off series of The Kindaichi Case Files.

Hajime manages to land a gig in the arrangements for the mystery novel award ceremony, where Fumi is a runner-up. The ceremony, however, is derailed when the grand-prize winner has gone missing from the ceremony and the screening of the award winners suddenly changes to a clip displaying a murder scene taking place that also shows a promotional banner including "Ayase", which is location of the mystery novel that wins the grand prize. Hajime, Fumi, and several others, as a result, find themselves trying to chase the perpetrator and discover the truth behind the murder case, which quickly proves serial.

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Tropes include:

• Bait-and-Switch: After the daughter of a CEO of the top client to Otowa PR decides to find a cafe while she's still tagging along Hajime for potential inspiration, Fumi decides to call him, but the phone conversation gets peppered with him seemingly groaning in pain to someone else, leaving her to wonder what Hajime is up to. It soon pans to Hajime and the daughter of a CEO of the top client to Otowa PR at a massage parlor as customers, and Hajime is having a rougher experience due to not being used to massages.
  Hajime: [thinking privately] I'm all broken inside...
• Bait-and-Switch Silhouette: Fumi and one other participant enter an old, unused house at night at one point while the serial murder case is still ongoing. They discover an image of a human figure sitting in a chair, get closer to investigate... and find that the human figure is actually a mannequin.^note  That being said, it's still plot-relevant, because the mannequin itself is wearing a business suit that turns out to belong to the final murder victim.
• Big Brother Instinct: Inverted. The guy a group of teenagers murdered is/was the culprit's older brother, with the motive being to avenge said deceased older brother.
• Bound and Gagged: All of the victims in this case arc suffer this fate as they're being murdered, and all but one are also found in this fashion in death as well.
• Cat Scare: When four people, including Fumi but not Hajime or Marin, reach the dilapidated house where they find the corpse of the first victim, they opt to leave and are alarmed by a sudden movement, before they find out that the movement was done by a cat.
• Continuity Nod: Kindaichi mentions to Marin that part of the reason he manages to get the promotional job for the mystery novel award ceremony instead of someone from a PR firm with prior experience for such events is due to the head of a large PR company owing him a favor for having solved the Poltergeist Mansion Murder Case, whose culprit was an employee in said large PR company.
  Marin: I guess it was a blessing from that disaster!
• Cruel and Unusual Death:
  • The teenager who was murdered in the case being perpetuated by the gang who would become murder victims themselves in the present-day case suffered a gruesome fate. Makabe, who relays the details of said crime to Kindaichi and Fumi, outright calls what the gang had done "lynching".
    Makabe: He and his two other delinquent friends kidnapped a 16-year-old high schooler from their town. They beat up the kid, punched, and kicked him many times... stabbed him with a knife, burned him with a lighter, and tortured him in several other unspeakable ways before finally murdering him.
  • While recounting the details about the culprit's actions against the final murder victim, who was the leader of the gang back when the gang members were teenagers, near the end of the case arc, Kindaichi remarks in The Summation that the culprit had the target Bound and Gagged inside the trunk of his car with a charcoal burner next to said target before lighting the burner and closing the trunk, leaving the target slowing dying from carbon monoxide poisoning while the target was conscious and awake, but trapped, the whole time.
    Kindaichi: A cruel method of execution, if you ask me.
• Dead Person Impersonation: The culprit confesses to pretending to be the gang's "recruit" while approaching the gang leader, after said "recruit" was already Driven to Suicide.
• Driven to Suicide:
  • According to the mystery novelist who wrote a book based on the murder committed by three teenagers and their "recruit", said "recruit", guilt-ridden over the murder and death of his Only Friend that he helped to commit due to pressure from the others (especially the leader), offed himself three years ago.
  • The culprit in the present-day murder case arc confesses that his mother, having already been fighting a lot of traumas in her life at that point, went mad after seeing the mutilated body of the victim, who was a son of hers, killed by the teenagers before taking her own life.
  • An In-Universe example is the Villain Protagonist of the grand prize-winning mystery novel, as he commits indiscriminate murders after being fueled by a desire for revenge due to his attempts to impress a girl having gone without reciprocation before ending his own life at the end of the novel.
• Fire-Forged Friends: This case arc marks Makabe's second appearance as an adult, and his interactions with Kindaichi are much more genuinely cordial than they were in the previous occasion, which fell into Teeth-Clenched Teamwork instead.
• Informed Ability: The finalists and winners of this ceremony are supposedly good mystery novelists, but the readers don't get to witness the details of their handiwork.
• Jack the Ripoff: A self-invoked, In-Universe example. The culprit, being a best-selling mystery novelist, penned a mystery novel winning the grand prize this year, in which the Villain Protagonist committed indiscriminate murders based on the location name "Ayase" before ending his own life, in order to conceal the true motive of pulling off a serial murder where the targets are actually connected in real life (again, In-Universe), using the location name "Ayase" as a cover, and setting the final murder victim up for a Deceased Fall-Guy Gambit.
• The Killer Becomes the Killed: After the perpetrators committed a crime of torturing and murdering a teenager back when they were teenagers themselves, the culprit of the present-day murder case returns the favor in kind to said perpetrators.
• Love-Interest Traitor: The culprit in this case arc is the boyfriend of Fumi. That being said, Kindaichi remarks to Fumi as the case arc is near its end that he genuinely loved her by pointing out he could have used Fumi to have her and Hajime cornered or, worse, framed as the culprit of his crime but never did so, instead setting the final murder victim up as The Scapegoat.
• Love Makes You Evil: An In-Universe example. The main character in the mystery novel winning the grand prize falls into this category, making him a Villain Protagonist because All Love Is Unrequited. He falls in love with a woman, who sends a text message asking him to go to Ayase, only to be told it's a wrong place. He tries it for the second location, only to be given the same response. He tries for one last time... and the messages stop, never to resurface. Since then, he spends the rest of the novel getting fixated on the word "Ayase" and, fueled by a desire for revenge, causes him to carry out indiscriminate murders in three locations, all of which bear the name "Ayase".
  Makabe: WHAT? OVER A GIRL?
• Minor Major Character: Marin is absent through much of the case arc, especially after the daughter of a CEO of the top client to Otowa PR connects her way into an interview with Kindaichi before following him along whenever she can through the rest of the case arc, in an attempt to find further inspiration for her future mystery novel work (during Kindaichi's work shift, no less), showing up only after the case is wrapped up at the end of the case arc.
  Marin: AARGH! WHAT THE HELL IS THAT WOMAN EVEN DOING? I DON'T WANNA DEAL WITH HER ANYMORE!
• Most Writers Are Writers: The award ceremony in this case arc is for mystery novelists.
• Never Suicide: The scene for the final murder victim is set up to make it look as though he had murdered the others before offing himself, and Kindaichi quickly finds evidence to support his belief that someone has murdered said victim as well as all others.
• Only Friend: A tragic example. The victim in the murder case 15 years ago was the only buddy to the teenager who consorted with a teenage gang after dropping out of school due to academic hardship. The teenager and his friend met the gang one day and his friend pleaded for the gang to let said teenager go, but the gang responded with violence instead, torturing and attacking the teenager's friend (and pressuring the teenager into doing so, too). After his friend was tortured and murdered, he — and eyewitnesses — provided testimony to the police after his friend's body was dumped in a river, but the damage was already done by then. According to the mystery novelist who wrote a book using this crime as source material, he turned himself in, was sent to a boys' reformative institution (the only one to have been sentenced for that; the gang members all served prison sentences instead), stayed cooped up inside his own residence after release, and committed suicide three years ago.
• Parental Abandonment: As the culprit states in his confession near the end of the case arc, the teenager who was murdered in the case years ago was his brother. After seeing his brother's mutilated body, his mother, having already been dealing with a lot of traumas in her life by that point, went mad before taking her life. His father, who had been taking care of her, disappeared following her demise, leaving the culprit to fend for himself.
• Pen Name:
  • The writer of the novel winning the award ceremony grand prize actually takes on a pseudonym.
  • Fumi, likewise, has a pseudonym while penning her mystery novels.
• Ripped from the Headlines: In-Universe. The murder case that was committed by those who end up as murder victims in the present-day serial murder case arc was the source material for a mystery novelist, who's among the participants in said present-day serial murder case. It was even titled "Teenage Demons".
• Screw the Rules, I Have Connections!: Played for Laughs, or lighthearted at least.
  • Kindaichi confesses to Marin at the start of the case arc that he manages to get the job of promoting the mystery novel award ceremony due to the combination of being the cousin of one of the finalists and a large PR company head owing him a favor for having solved a serial murder case instigated by an employee in said PR company.
  • One of the participants in this case is the daughter of a CEO of the top client to Otowa PR, who, after learning about Kindaichi's heritage and past involvements in various murder mystery cases, insists on holding an interview with Kindaichi as potential inspiration for her future mystery novels, and she uses her father's business association with the Otowa PR company head to have her interview with Kindaichi granted during his working hours.
    Kindaichi: *thinking privately* Can I write that off as business expenses? I guess it'll be considered as part of work...
• Sequel Hook: The case arc ends with Kindaichi and Marin being given a promotional job assignment for an exhibition event based on another mystery novelist. Marin senses another mystery case on the horizon, which makes Kindaichi wary.
• Spit Take: One participant in the murder case arc, after handing a copy of a book he wrote based on a murder that took place years ago and is connected to the present-day murder case, talking to Kindaichi, and listening to his deductions, compliments Kindaichi on his investigative prowess by bringing up the facts that he's the grandson of the great detective, Kosuke Kindaichi, and that he had solved his fair share of cases 20 years ago. The sheer shock from such knowledge said participant divulges causes Kindaichi to spit out his drink.
  Kindaichi: (nervously) A-Ah, how do you know that...?
  Novelist: I have been doing my own investigations and writing mysteries for 30 years, you know... I've got contacts in the police, so of course I'd know who you are.
• Teens Are Monsters: The victims were the perpetrators in a murder case that they committed back when they were teenagers. There was one other person who got consorted with them as a teenager, and a close friend of said other guy tried to get him away from them, but they, acting on their leader's orders, attacked said close friend and exerted many violent acts on him before murdering him. The culprit of the present-day serial murder case is related to the murdered teenager and makes sure The Killer Becomes the Killed, and a mystery novel based on this murder was even titled "Teenage Demons".
• Tempting Fate:
  • The first example takes place during Kindaichi and Marin's dialogue while they observe the award ceremony.
    Marin: I hope this doesn't lead to another tragedy.
    Kindaichi: H-Hey! Don't say things like that!
  • The last example occurs right at the end of the case arc, after Kindaichi and Marin have just been handed another promotional job assignment featuring an exhibition event based on another mystery novel, overlapping this trope with Sequel Hook.
    Marin: In an event like this, I smell a mystery coming along.
    Kindaichi: Erm, Ms. Hayama... don't say anything that might just tempt fate...
• Villain Protagonist: In-Universe. The main character in the mystery novel winning the grand prize overlaps this trope with Love Makes You Evil, as the murders he commits in the novel are a result of a girl who asks him to reach a place before dropping any and all contacts with him.