Zaregoto is a light novel series by the exceptionally prolific author, NisiOisiN. There are nine novels total, with the first two being translated into English by Del Rey Manga. The series was later rescued by Vertical, but they have only published three novels. It has a spin-off series focusing on the Zerozaki family, the Ningen series, where seven novels have been published. The author has also written a series of short stories about Aikawa Jun, Saikyō, collected into five volumes. In February 2023, a new novel in the series was released. Though the official numbering places it as the tenth book in the main series, it's a Distant Sequel starring Tomo and Ii-kun's daughter Jun Kunagisa as the new protagonist.
The series is narrated by the college student Ii-chan (or Ii-kun, or Ii-tan) as he tries his best to be a "passive observer" of the strange characters, mysteries, and inevitably, murders around him. The cast of the series is quite extensive, except most characters only appear or survive for a single novel. The only other frequent recurring characters are "The Blue Savant" Kunagisa Tomo, and "Humanity's Strongest" Aikawa Jun.
The Kubikiri Cycle ("The Beheading Cycle") introduces Ii-chan and Kunagisa as they are invited to the secluded Wet Crow's Feather Island for a gathering of geniuses. The island is owned by Akagami Iria, a wealthy disinherited heiress who has been living in exile on the island with her maids for the last five years. When one of the guests is found dead - decapitated - Iria decides to ask Aikawa Jun to solve the murder. But it will take several days before Jun will arrive, and Ii-chan decides to investigate the mystery while they wait.
The Kubishime Romanticist ("The Strangling Romanticist") takes place two weeks after the Kubikiri incident, at Rokumeikan Private University. While eating lunch in the university cafeteria, Ii-chan meets a girl named Aoii Mikoko, a friend he doesn't remember. She later invited him to her friend's birthday party for tomorrow, and with nothing better to do, he agrees. While buying birthday presents for tomorrow, he encounters the infamous serial killer of Kyoto Zerozaki Hitoshiki...The next day, Ii-chan and Mikoko arrives at her friend's apartment and with three other people including the host, they started the party. However, the morning after, the host is found strangled to death.
An OVA animated adaptation of the first novel has been released. The first two novels of the Ningen series were also adapted as manga. There is also a crossover gag manga series with Pretty Boy Detective Club and Monogatari Series as well.
This series provides examples of:
- The Kubikiri Cycle: The Blue Savant and the Nonsense Bearer
- The Kubishime Romanticist: Hitoshiki Zerozaki, Human Failure
- The Kubitsuri High School: The Nonsense Bearer's Pupil
- Psycho Logical (Part One) Gaisuke Utsurigi's Nonsense Killer
- Psycho Logical (Part Two): Sour Little Song
- Cannibal Magical: Niounomiya Siblings, Masters of Carnage
- Nekosogi Radical (Part One): The Thirteen Stairs
- Nekosogi Radical (Part Two): Overkill Red vs. The Orange Seed
- Nekosogi Radical (Part Three): The Blue Savant and the Master of Nonsense
- Kidnap Kidding: The Blue Savant and the Nonsense Bearer's Daughter
- Zerozaki Soushiki no Ningen Jikken (Zerozaki Soushiki's Human Experiments)
- Zerozaki Kishishiki no Ningen Nokku (Zerozaki Kishishiki's Human Knock)
- Zerozaki Magashiki no Ningen Ningen (Zerozaki Magashiki's Human Human)
- Zerozaki Hitoshiki no Ningen Kankei (Zerozaki Hitoshiki's Human Relationships)
- Niounomiya Izumu to no Kankei (Relationship with Niounomiya Izumu)
- Mutou Iori to no Kankei (Relationship with Mutou Iori)
- Zerozaki Soushiki to no Kankei (Relationship with Zerozaki Soushiki)
- Zaregototsukai to no Kankei (Relationship with Zaregototsukai)
- Action Mom: Hitoshiki's mother (and Soushiki's adopted mother) is implied to have been one, as a member of the Zerozaki family. Houko's mother and Moeta's stepmother, Yamiguchi Hyoui, is a ninja-like assassin who used to team up with her stepson and faced Aikawa Jun.
- All There in the Manual: The Zaregoto Dictional, a "dictionary" about the series published after the completion of the main series.
- Amazon Brigade: Shiogi, Tamamo and Ichihime used to be one back in middle school fighting the Zerozaki family.
- Badass Family: All seven of the Killing Names could count. The six Cursing Names might count as well.
- Battle Couple: Niounomiya Izumu and Zerozaki Hitoshiki. They are formidable fighting together. Shame it only happened once
- Blade Enthusiast: Zerozaki Hitoshiki. He has knives hidden all over his body.
- Blue-and-Orange Morality: Most of the characters in the series don't care about morality. It is most obvious in the Zerozaki family: They kill people because they are serial killers and that's it. One of the few people with a strong sense of justice is Jun.
- Catchphrase: "It's a masterpiece" by Zerozaki, often echoed by Ii-chan
- Closed Circle: Wet Crow's Feather Island. Because of Iria's dislike for police, the murderer was never arrested.
- Designer Babies: Aikawa Jun and Omokage Magokoro were designed to become "the strongest human", using different means. Jun was considered a failed project by her father so he abbandoned it. But his collegues picked up where he left it and created Magokoro. By contrast, Kunagisa Tomo is the "natural-born" genius out of the three. It is implyed her situation is due to Royal Inbreeding in the Kunagisa Clan.
- Family Theme Naming: Everyone in the Zerozaki family has 識"shiki"(for male members) or 織"ori"(for female members) in their given names. A different example is the Niounomiya family, where the family names of the Niounomiya and their associates are taken from chapter titles of The Tale of Genji.
- Gender-Blender Name: Aikawa Jun. Ii-chan thought she was a man before actually meeting her.
- Heel–Face Turn: All of the 13 Stairs betray the Big Bad Saitou Takashi in the end, some even on his orders.
- Heroic BSoD: Ii-chan suffers from one after Izumu's death and Jun's defeat to Magokoro. Kunagisa talks him out of it.
- Hero of Another Story: Members of the Zerozaki family in the Ningen series and Aikawa Jun in some short novels.
- Idiot Savant: Kunagisa has been diagnosed with Savant Syndrome, she's unparalleled with anything involving computers, but helpless in many day-to-day activities.
- Insufferable Genius: Aikawa Jun, as well as a number of the guests on Wet Crow's Feather Island, particularly Ibuki Kanami and Himena Maki.
- Jack of All Trades: Aikawa Jun is able to do anything and everything.
- Jekyll & Hyde: It may not look like it, but the two Niounomiya twins are split personalities. The weird part comes in when Rizumu (the main person, usually shown red) is a girl and Izumu (the crazy one, usually shown green) is a guy. To show even more differences between the two, Rizumu is usually the light-headed personality and the detective, whereas Izumu is the killer and wears a straitjacket as a fashion statement because he thinks killing with his hands is boring.
- Locked Room Mystery: The murders on Wet Crow's Feather Island.
- Lonely Rich Kid: Akagami Iria, an exiled heiress who surrounds herself with various geniuses for entertainment. And perhaps Kunagisa Tomo.
- Murder Mystery: The bulk of the series involves our apathetic protagonist getting involved with one murder scene to the next one. What makes this different from other examples is the the Mc ABSOLUTELY has no interest in being a detective but is forced to act as one anyway.
- Mystery Magnet: As Ii-chan comments himself, he's become far too accustomed to seeing dead bodies.
- Never One Murder: Subverted, as Akane faked her own death in The Kubikiri Cycle. Played straight in almost all the other books.
- Never Suicide: Subverted. Mikoko killed herself, and Ii-chan made the scene look like a murder.
- Ninja: The Yamiguchi family bear a lot of similarity to ninjas, but they are never named such in-universe.
- Numerical Theme Naming: The Kunagisa clan and all their associates have names with numbers from 1 to 9. Curiously, the number 7 officially doesn't exist, but it is mentioned in the spin-off as a secret team only known to the main family.
- One-Gender School: Sumiyuri Academy (or the Hanging High School) is an all girls school.
- Professional Killer: Niounomiya Izumu and perhaps everyone of the Niounomiya family since they are killers for hire. Yamiguchi might count as well, but the difference is that the members of the Yamiguchi family choose their own masters and are only loyal to their masters. And there is the Sumiyuri Academy, where girls are trained to be some kind of mercenary...
- Psychic Powers: Himena Maki is a world-renowned psychic. She's capable of precognition up to two years after her introduction, at which point she will be brutally murdered and mindreading, which she uses to insult the main character about his major personal problems every chance she gets.
- Reasonable Authority Figure: The Kyoto Police, especially Sasa Sasaki. She is friends with Jun, so it is understandable.
- Serial Killer: Zerozaki Hitoshiki killed 19 people before he was stopped by Aikawa Jun. And to think his whole family are just like him...
- Theme Twin Naming: The Niounomiya siblings (whether they are twins is debatable) Izumu and Rizumu, the Miotsukushi twins Misora ("Deep Sky") and Takami ("High Ocean"), the Akagami twins Iria and Odetto (Iliad and Odysseus), the Chiga triplets Akari, Hikari and Teruko (all three names mean "light, brightness"), the Saitou twins Jun (順) and Jun (準).
- Tiny Guy, Huge Girl: Hitoshiki is only 150cm while Izumu is said to be very tall.
- Tragic Dropout: Hitoshiki, he dropped out of middle school after his whole class was killed by Izumu.
- Wholesome Crossdresser: Ii-chan is forced into this in order to infiltrate the Hanging High School.
