The story revolves around Amateur Sleuth/Private Detective Tenkaichi Daigorô, the main character of the fictional Tenkaichi Series, as he solves various criminal cases while being bound by the "conditions" of the Detective genre (which suspiciously seem like a different word for "tropes"). Two others are aware of this: Ogawara Banzo, fully aware of his role as the Clueless Detective and Tenkaichi's sidekick; and Fujî Mana, the female rookie officer and potential love interest for Tenkaichi, who slowly learns about the various conditions they have to live by.
Knowing they live in a fictional series allows them to enter a "backstage" room that only they can see to discuss the story and the "conditions" within the Tenkaichi series while standing outside of it. Each episode revolves around a different murder mystery theme/trope and discussing and playing with all the tropes that come along with it.
This show provides examples of:
- Accidental Misnaming: Banzo continuously gets Moriyama's name wrong in episode nine when he's trying to set himself up as a main character in his Spin-Off, starting off with names that are slightly similar that get more and more random. Justified because it isn't the real Banzo.
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Acting for Two:- In one episode, a man and his female cousin are played by the same actor, and it takes a long time for anybody to accept that she's really a woman. Justified because she isn't a woman and it's the man in disguise.
- Kimura Yuichi, Banzo's actor, also plays Kaneda (who pretends to be Banzo throughout episode nine).
- Affectionate Parody: The creator, Higashino Keigo, is a famous mystery novel writer and through this work, he parodies the genre.
- Air-Vent Passageway: Banzo uses the massive, unsecured air vent in his prison cell to escape.
- Always Murder: Lampshaded. But not necessarily true as Seichiro's death in the second episode was an accident.
- Amateur Sleuth: Tenkaichi (who also doubles as a semi-professional Private Detective) and all of the victims in the finale were amateur detectives as well.
- And the Adventure Continues: They now solve crimes in space.
- Animal Reaction Shot: The dog's reaction in the The Summation in the first episode.
- Attempted Rape: In the first episode, Reika tries to rape Tatsuya while he's unconscious so she can have his child, but he's fortunately rescued by Kimiko, his fiancee.
- Asshole Victim: Multiple.
- Ousama, in the third episode, was extremely disliked and nobody was upset when he died. Subverted (slightly) when it turns out he did love his family but he was bad at expressing his love and they didn't want to listen.
- Lampshaded in episode seven:
Tenkaichi: "However, going on the behaviour of Jirou last night it was almost like he was yelling: "Hey! I'm about to be murdered!" I couldn't bear to watch."Banzo: "When a frivolous tight wad shows up before a great detective, nine out of ten times he's going to die." - Back from the Dead: Banzo and Tenkaichi in the ending scene.
- Bathtub Scene: One with Tenkaichi to show off the fact he never takes his hat off.
- Big Secret
- Biting the Handkerchief: Akira does this in the second episode after Osuma, his boyfriend, confesses to murdering Seichiro.
- Bloody Murder: In episode two, Tenkaichi deduces that the murderer froze blood of the same type of the victim and stabbed him with it, so the "weapon" would eventually melt and get lost amoungst the victims. Subverted when it turned out it wasn't murder at all.
- Breaking the Fourth Wall: One could say the series provides an example of this trope. The main characters will enter a special dimension where they can talk about the progress of the case and occasionally explain the conditions to the people watching the show.
- In the fourth episode, Tenkaichi directly addresses the audience and tells them how to and how not to work out who the murderer is (as mystery audiences do).
- In the finale episode, Tenkaichi finds a collection of the "Tenkaichi" novel series.
- Busman's Holiday: Fujii takes a holiday to a hot springs and is forced to solve the murder that's caused by her presense.
- Call-Back: There's usually references to previous episodes and murders. In one episode where Fujii is chasing a murder suspect she runs into the woman who helped them solve the Nursery Rhyme Murders who screams "The nursery rhyme is back!" (it's never mentioned again).
- In the final episode, Banzo calls Fujii by the nickname he called her in the first episode, "Paper".
- Cardboard Prison: Banzo escapes prison in the final episode with ease.
- Cartwright Curse: Inverted. Tenkaichi states that if Fujii tries to date him in the finale he's going to die.
- Catchphrase:
- Tenkaichi's is his introduction
- Banzo's: "Tenkaichi, this is no place for an amateur detective!"
- Catch Phrase Interruptus: Banzo's is interrupted when Takaichi tells him was a witness to a murder so he needs to be treated nicely.
- Cat Fight: Between the murder victim's wife and lover in the second episode. Tenkaichi and Banzo look disappointed when Fujii stops them.
- Chalk Outline: Used straight.
- Character Title: An In-Universe example, as the fictional series the characters are apart of is simply called the "Tenkaichi Series".
- Chekhov's Gunman: Discussed after it's revealed that the murderer in episode three was Yamada, a man who had never been mentioned and was only on screen twice in the background, with absolutely no lines. After Tenkaichi points out where he had been spotted Banzo says that it's "safe" while Fujii says it was utterly unfair as nobody would have worked it out.
- Chick Magnet: Keita and Tenkaichi, less so.
- Closed Circle: Used repeatedly, straight and lampshaded.
- Clueless Detective: The story dictates the police chief is this, but actually subverted in some cases, in which the Great Detective totally misses the truth and the chief will not point that out, although he notices. He also accepts and leaps to ridiculous conclusions when he's quite aware they aren't true.Banzo: "I know I'm talking nonsense!"
- Clueless Mystery: Parodied.
- Costume Porn: In-Universe, in Fujii's episode that's aimed at the middle-aged women "viewers", who would enjoy seeing lots of different costumes so Tenkaichi makes her change at regular intervals.
- Creepy Crossdresser: Rumi-chan, though the crossdressing isn't portrayed as creepy.
- A Day in the Limelight: Fujii gets her own episode, including her own opening credits, theme song and title.
- Dead Hat Shot: When Tenkaichi dies.
- Death by Falling Over: Seichiro's accidental death in the second episode, when his femur broke and stabbed his hand and his chest.
- Detective Drama: Well...
- Detective Mole: Discussed when Fujii jokingly accusses Tenkaichi of being the murderer (because all of the other suspects were so suspicious that it made the plot "dull"). Banzo said it was a stupid idea because the show would be over if it were true.
- Subverted when it looks like Banzo murdered two people, when it was actually his old friend, Kaneda, who looks exactly like him and frames him.
- Disguised in Drag:
- Banzo disguises himself as a woman who is under the threat of death to save her.
- In one episode, a woman disguises herself as her husband so he has an alibi while he pretends to be a woman who he planned on framing for the murder
- Driven to Suicide:
- In the first episode, Kimiko didn't commit suicide but was murdered by Saeko, who did kill herself after she knew she would get caught.
- Banzo's daughter, Hanako, committed suicide after the father of her fiance, Jiro, forced him to dump her and marry another woman. This is why Kaneda (while pretending to be Banzo) murders the two of them as revenge.
- Dying Clue: The theme in the third episode after Ousama leaves what looks like "W-E-X" written on the carpet. Throughout the episode more and more messages crop up and it's stated early on that Ousama had terrible handwriting. One said "Vacation Ousama" which they presumed meant Ousama's son-in-law as he was on vacation that day but had a solid alibi. It turns out that while writing the second one (that was one of his favourite sayings) he was murdered and tried to write a message. He couldn't see very well and wrote half of it on the paper and half on the carpet. He threw the paper outside (believing it had the entire message) for somebody to find. It said "Call a doctor!"
- Tenkaichi catches a man slipping a love letter to Ousama's widow and tells him that he picked a bad day to leave a written message.
- Eventually one turns up that says Ryuichi (Korosu) Kill and Tenkaichi throws it away because it ruined the "mysterious mood". It was actually a note left by the maid after Ryuichi called to say what he wanted for dinner and the maid only wrote certain syllables as he spoke fast.
- Eat the Evidence: Discussed in the second episode, when the biggest mystery is what the murder weapon is. Tenkaichi uses the example of a sharpened candy cane.
- End-of-Series Awareness: In the second to last episode Banzo comments that the show must be nearing a close. In the final episode (where checkered flags on a race track get waved blanently in front of the camera), Banzo, Fujii and Moriyama all receive telephone calls that result in something important happening to them (e.g. Moriyama is being transferred) to give a sense of conclusion to the viewers:Tenkaichi: "The reason behind the turning point in life which all the story's characters are experiencing... The theme this time is The Finale!"
- Banzo and Tenkaichi become a little depressed throughout the episode because they know they'll never see each other again afterwards. Subverted when this was all a trick from the author because the series hasn't actually ended and they now solve crimes in space.
- "Eureka!" Moment: Once per Episode to help Tenkaichi solve each case. They usually have little to do with the situation at all.Tenkaichi: "It's not like hints to solve the case would suddenly appear." [hint that helps solve the case appears]
- Everybody Did It: Discussed and dismissed as a possibility in episode four as Tenkaichi said it was an over-used plot. Nobody did it.
- Everyone Is a Suspect: The theme of episode four.
- Faint in Shock:
- Several overly emotional wives faint when they learn that their husbands have been murdered
- Tenkaichi tends to faint when he's scared.
- Faking the Dead: The murderer in the final episode, Shijou.
- False Confession: Episode Two: Osuma confesses to Seichiro's murder (which was actually an accident) after Banzo convinces him to so Tenkaichi wouldn't be seen as making a mistake. Banzo promises that he'll go free after The Summation.
- Fanservice: In-Universe during the Hot Springs Episode to "raise male viewership". When Fujii refuses to take part, because she's busy solving a murder, Moriyama goes in instead.
- Femme Fatale: Subverted with Saeko in the first episode who, while strict on her stepson, was a kind woman- who merely looked and acted like a femme fatale on the outside. Double subverted since she has a dark past, murdered her blackmailer and murdered the woman trying to steal the inheritance.
- Fish-Eye Lens: Used in the "backstage" room where the characters can be "out of character" and discuss the events of the story.
- Forgets to Eat: Tenkaichi
- Frame-Up:
- Banzo frames Jiro for his father's murder and fakes a suicide, then it's subverted when it's revealed that it's somebody else pretending to be Banzo, knowing Tenkaichi would see through the original trick, to frame him.
- Shijou planned to have Tenkaichi framed for the murder of all of the amateur detectives and then kill him.
- Functional Genre Savvy: Tenkaichi and Banzo can always tell within the first few minutes what type of murder mystery they're in and what needs to be done to advance the plot.
- Fun with Acronyms: Tenkaichi refers to wills as "ODA" meaning "Official Dying Message" - it's "DA" because of the pronunciation of "dying". Fujii points out the flaw in the acronym (and the pointlessness of it), Tenkaichi instantly changes it to "ODM" and when Fujii calls him out on it, he refuses to continue The Summation.
- Gainax Ending: Banzo dies trying to save Tenkaichi, who then dies saving Fujii and after Tenkaichi's book series disappears (because the main character dies) Fujii wakes up on a space station solving murders with Tenkaichi and Banzo, who are both alive.
- Genre Deconstruction: The premise of the show. Most tropes used in the book and the series are deconstructed, parodied, subverted, invoked or exaggerated in some way.
- Genre Savvy: Ogawara and Tenkaichi are aware from the beginning that they are just characters in a novel, and they try their best to fulfill their "conditions". Fujî will get to learn that truth early in the first case.
- Gold Digger: Many one-episode characters.
- In the first episode, Kimiko and this is the reason Saeko murders her.
- Yoshimi in the second episode was one towards Seichiro.
- Yumie in the third episode towards the murder victim.
- Goodbye, Cruel World!:
- In the first episode, a fake letter is left to cover Kimiko's murder as a suicide.
- One is left in episode eight, which is quickly dismissed by Fujii who goes off to prove it was a murder.
- Grand Finale: The theme of the final episode as it's both the ending of Lessons for a Perfect Detective Story and the Tenkaichi series itself. Subverted when it isn't the end of the Tenkaichi series.
- Great Detective: Tenkaichi's very first Condition.
- Great Escape: In the finale, Banzo gets arrested for being the serial killer, is instantly put in prison and escapes just as quickly.
- Hand Wave: A Once per Episode occurrence, which are always lampshaded and shrugged away - justified as the characters are aware they're in a fictional world and sometimes these things just happen. For example: when Fujii doesn't know the reason behind the suicide note in her own episode, a couple of men hold out the answer on a piece of paper for her. There's no explanation as to who they are or why they know the answer; Fujii is ordered just to get on with it.
- Happily Adopted: Tatsuya from the first episode, as Saeko was only fifteen when he was born and his adoptive parents had just had a stillborn child the situation was rather perfect.
- The Hero Dies: Tenkaichi pushes Shijou, who has a bomb strapped to his chest, out of the building Fujii is in and they both get blown up (and Fujii is safe). Then his book series disappears as he, the main character, is dead. Subverted when he comes back in the sequel-in-space.
- Heroic Sacrifice:
- Banzo takes numerous bullets for Tenkaichi so he can conclude the series and then Tenkaichi wrestles with Shijou (who has a bomb on him) outside so Fujii doesn't get blown up.
- In one episode a man stabs himself so his evil alter ego wouldn't murder his daughter.
- Hopeless Suitor: Moriyama for Tenkaichi, as Banzo reminds her every single episode.
- Hope Spot: Discussed in the finale on how the show could end.
- Hot Springs Episode: Merged with Fujii's Day in the Limelight episode, as Banzo and Tenkaichi point out this is the "Two-Hour Suspense" episode aimed at middle-aged women who want to see luxury. Mid-way through Fujii is told to use the onsen to keep viewers from changing the channel, but she refuses. Moriyama goes in her place.
- Hypercompetent Sidekick: Keita to Tenkaichi, who repeatedly kicks him down a few notches so his pride doesn't suffer but always depends on him to find things he can't/doesn't want to himself.
- Identical Stranger: Banzo looks the exact same as his old friend, Kaneda (though they didn't look the same when they were younger).
- Idiot Ball: In the first episode, Saeko had concrete evidence that Kimiko was cheating on Tatsuya and treating him as a Meal Ticket. Instead of simply telling Tatsuya, she decides to murder her and eventually get caught.
- Insistent Terminology: In the final episode the author says it's the final episode of the Tenkaichi series, which isn't the case. Fujii calls him a liar but Tenkaichi and Banzo say it was a trick that the audience fell for.
- Interrupted Suicide: Tenkaichi stops Yamada from killing himself in the third episode.
- In-Universe Nickname: Fujii receives a different nickname from Banzo each episode.
- Kid Detective: One of the amateur sleuths in the finale.
- Lampshade Hanging: Plenty, such as how Moriyama got the photographs all of the people involved in the murder-of-the-week so she could make a chart.
- Lights Off, Somebody Dies: In the finale episode, Tenkaichi tries to stop the lights from going off because he knew somebody would be dead when they went back on again. He was right.
- Little "No": Episode Two: After Tenkaichi accuses Osuma as being the murderer, Seichiro's death is discovered as an accident but as Tenkaichi isn't allowed to be wrong Banzo (after explaining the "conditions") asks Osuma to fake a confession. Osuma refuses with a small no.
- Locked Room Mystery: One of the "conditions" and the theme of the first episode, which was caused by the heavy snow deforming the house, meaning the door couldn't open properly. The murderer made it look as though the door was locked from the inside when it was eventually broken down.
- Lying Creator: In-Universe and lampshaded in the final episode. When the creator of the Tenkaichi series said it was the final episode, when in fact it wasn't - which means that Banzo's and Tenkaichi's deaths are not permanent.
- Mama Bear: In episode one, Saeko is the real mother of her step-son, Tatsuya. When she finds out his fiancee, Kimiko, is a Gold Digger Saeko murders her to protect him.
- Medium Awareness: Tenkaichi, Banzo and Fujii are all aware they're in a fictional series - while it's referred to as a novel series, they do abuse the visual medium. In the third episode, when nobody recognised the man Tenkaichi accussed of murder, he wound back the episode to when he appeared (when Tenkaichi wasn't there) and jumped around and pointed at him as the rest of the characters carried on as they did the first time.
- Mystery Magnet: Discussed; whenever either of the main three go on a holiday: there will be a murder.
- Mystery of the Week: With every episode there's a murder and solving the twist/mystery - the two aren't always the same. It's also not something the other characters necessarily care about. In the first episode, nobody cared how the locked room mystery was formed after the murderer had been revealed.
- Never Bareheaded: Tenkaichi never takes off his siganture hat.
- No Name Given: Various characters that Tenkaichi and Banzo deem unimportant but are there just to confuse the viewer such as A-san, B-san and C-san in the second episode.
- Nursery Rhyme: The "Nursery Rhyme Murder" episode where murders follow what happened in a nursery rhyme (that they don't know the full lyrics of).
- Paper-Thin Disguise: Rumi is clearly a man, subverted when Tenkaichi states that it's clearly the Red Herring of the episode. Double Subverted when it really is Yaichiro and Tenkaichi just needed to make sure.
- The Perfect Crime: Another "condition", exaggerated to the point that the criminal had to help the detective to solve it (and yet, he ignored the truth out of pride).
- Picky Eater: Tenkaichi, a vegetarian who doesn't drink alcohol and doesn't eat carrots (even though he finds them delicious).
- Pit Girls: A victim in the final episode is one.
- Plot Armour:Tenkaichi: "No matter what kind of danger, I'm still the main character! I won't be killed."Fujii: "Unlike your usual self, you're pretty manly this time."Tenkaichi: "Exactly! How can the main character die before solving the mystery? If I die like this it'll be a weird ending."
- Police Are Useless: Lampshaded by Ogawara from the very beginning, then subverted in various occasions.
- Postmodernism: The main three characters are aware they're in a book series called the Tenkaichi Series and they play around with this knowledge throughout. In the final episode, they meet other fictional amateur detectives who each get murdered and, when they do, their series of books disappears. The murderer is a murder-mystery lover who realises that the old style of detective novels are now out of fashion and knows they'll all be forgotten so he wanted to kill them all so they'd be over nicely - it was also a set-up to get Tenkaichi framed and murdered.
- Pride: Tenkaichi's main vice and is used to his advantage in one episode where he concludes that Rumi is actually a man because no woman would turn Tenkaichi down when he proposes.
- Private Detective: Tenkaichi sometimes receives jobs, such as investigating Ousama's wife.
- Reactive Continuous Scream: One is caused when Tenkaichi catches a man slipping a note to a woman under her door and starts screaming.
- Recycled In Space: The ending. After Banzo and Tenkaichi die, Fujii wakes up on a spaceship where the three of them solve murders because it wasn't really the final episode and this is the sequel.
- Red Herring: Plenty of them and Banzo takes all of them as serious options as part of his "conditions".
- Resigned to the Call: Tenkaichi says that he never wanted to be a detective but since he has no choice he might as well do it right. Fujii and Banzo feel similarly in terms of their characters and conditions.
- Retcon: Parodied, as in the last episode Banzo's family is completely recreated. Originally he had an estranged Japanese wife and a teenage daughter, Hanako, who killed herself; in the final episode he has a blonde non-Japanese wife and a child-aged daughter (also blonde) who has another name. Banzo lampshades the difference but accepts it.
- Sequel: The Tenkaichi series has one set in space.
- Serial Killer: The Amateur Detective Serial Murderer in the final episode.
- Sharp-Dressed Man: Tenkaichi.
- Shout-Out:
- The openings include a silhouette of Sherlock Holmes.
- In the second episode, Tenkaichi says he was trying to watch the Ariake Meteor Shower, which is a reference to the mystery series Ryusei no Kizune.
- The drama Keita has a small part in has the exact same plot as Ryusei no Kizune.
- In one episode, Fujii dones a forensic officer's uniform while The Who plays over the top.
- When Banzo is arrested , he has the map of the prison on his chest to help him escape.
- Shipper on Deck: As one of Fujii's conditions is that she fall in love with Tenkaichi, Ogawara is always willing to push them together whether she likes it or not. His efforts include leaving the room so the two can have a scene alone, and making sure to point out any hint of jealousy Fujii shows towards Tenkaichi. He's quite pleased when they start becoming closer of their own accord.
- Show Within a Show: The "Tenkaichi" series within this book/show, the biographical television series done about Tenkaichi by a television producer, Fujii's "Two-Hour Suspense" (that was adapted from a novel that Tenkaichi owns) and Banzo's Spin-Off.
- Spin-Off: Banzo gets his own in episode nine, causing him and Tenkaichi to fight for viewership.
- Summation Gathering: Once per Episode. Fuji messes up collecting enough people in the room in the first episode (seeing that there's no point in having people present who are obviously not the murderer or unrelated to the case). Tenkaichi demands certain things for his summation to be perfect: having enough people and for the murderer not to confess before he can say who it was.
- Straight Gay: Osuma and Akira in the second episode.
- Stunned Silence: Tenkaichi's horrorified reaction to multiple things such as when somebody steals his bicycle seat and replaces it with a cabbage.
- Stunt Double: Parodied In-Universe when Fujii is attacked in an episode, her stunt double takes over while she watches.
- Taking the Heat: In a flashback, Banzo said he stole a girl's cheerleading uniform to protect his friend - this in fact works in his favour as she's happy he felt so passionately about her that he felt the need to do such a thing.
- Thriller on the Express: Banzo notes that murders will always happen at certain times around him, Tenkaichi or Fujii when they're not working - one of them being when they're on a train.
- Tsundere: Fujii.
- The Unreveal: In episode five it's never revealed what the solution to the timetable-alibi was (as Tenkaichi says it's more interesting that they never know/doesn't want to know the solution that he didn't work out himself) or who stole Tenkaichi's bicycle seat.
- Victim of the Week: No exceptions.
- Wig, Dress, Accent: In episode seven, Machiko pretends to be her husband so he has an alibi while he kills Jirou. Yaichiro also dones these three to act as Rumi.
- Will They or Won't They?
- Wrong Genre Savvy: The amateur detectives in the finale episode aren't fully aware they're in a Ten Little Murder Victims situation and believe they're the main characters in their series, so they go off separately to catch the murderer (as they would in their own series) but get themselves killed - Tenkaichi and Banzo point out that their dialogue before they die is blanently highlighting their near demise.
