Zaregoto

Zaregoto is a Light Novel series by the exceptionally prolific author, Nisio Isin. There are currently 9 novels total, with the first two being translated into English by Del Ray Manga.

The series is narrated by the college student Ii-chan (or Ii-kun, or Ii-tan) as he tries his best to be an "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. There is also a spinoff known as The Ningen Series that focuses on the Zerozaki family.

This series provides examples of:
Series Overview
 * 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


 * Bunny Ears Lawyer - Most of the guests on Wet Crow's Feather Island.
 * Catch Phrase - "It's a masterpiece" by Zerozaki, often echoed by Ii-chan
 * Closed Circle - Wet Crow's Feather Island
 * Doppelganger - Zerozaki, despite looking nothing like Ii-chan, is described as this.
 * Genki Girl - Aoii Mikoko, and Kunagisa, to an extent
 * Hikkikomori - Kunagisa
 * 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.
 * Japanese Delinquents - Atemiya Muimi
 * Knife Nut - Zerozaki
 * Locked Room Mystery
 * Lonely Rich Kid - Akagami Iria, an exiled heiress who surrounds herself with various geniuses for entertainment.
 * Meaningful Titles - By the boatload.
 * Mystery Magnet - As Ii-chan comments himself, he's become far too accustomed to seeing dead bodies.
 * Names to Run Away From Really Fast - "Humanity's Strongest," "Overkill Red," "The Most Powerful Private Contractor in the World," a.k.a. Aikawa Jun
 * Never One Murder
 * Never Suicide -
 * Oblivious to Love - Ii-chan,
 * One Gender School - Sumiyuri Academy (or the Hanging High School) is an all girls school.
 * Only Known By Their Nickname - The narrator, Ii-chan.
 * Punny Name - Tomoe Emoto, Nanami Nanananami, Kasuga Kasugai... and much more.
 * Psychic Powers - Himena Maki is a world-renowned psychic. She's capable of precognition  and mindreading, which she uses to insult the main character about his major personal problems every chance she gets.
 * Serial Killer - Zerozaki
 * Twist Ending - Nisio is very, very fond of these.
 * Unreliable Narrator
 * Wholesome Crossdresser - Ii-chan is forced into this in order to infiltrate the Hanging High School.
 * You Gotta Have Blue Hair - Kunagisa