“A story should be written in the eyes of God.” That’s the narrator’s job: to tell the story in an unbiased, all-seeing point of view. But once a human starts narrating, many things are lost to opinion and bias — after all, they’re just human.
Take Ryuunosuke Akutagawa’s short story, “In a Grove”: A samurai is killed in a bamboo grove; he is found stabbed through the heart with his own sword. Witnesses are called in, three suspects are to be tried — an infamous bandit, the samurai’s girlfriend, and the deceased samurai, through a spirit medium. Each of them provides a testimony, but all of them are equally believable! Who is lying? Which one of them actually killed the samurai?
Ryuunosuke Akutagawa: trolling readers since 1922
This is the concept of the unreliable narrator: the biased narrator who deceives the viewer, injecting their own opinion into the story. This is when God stops caring about biases and leaves the narrating to a human — the imperfect, opinionated person who, whether or not it is intentional, blurs the line between truth and fiction, fact and opinion.
The power of the unreliable narrator can be clearly seen in the mystery genre, with works where even the storyteller goes out of their way to be as unhelpful as possible in giving clues to the reader. The When They Cry series is a notorious example of abusing this for effect — Umineko no Naku Koro ni, for example, is not a traditional mystery novel; it intentionally tries to obfuscate clues with flamboyant displays of magic, distracting the reader from the mystery and making the reader ask, “Was this murder done by a human, or a witch?” Similarly, Higurashi no Naku Koro ni abuses the unreliable narrator to hide clues, but for Higurashi, the unreliable narration adds more to the sense of horror and paranoia — by twisting the narration, everyone else seems to be after the protagonist; suddenly, it’s as if the reader is suffering the same delusional paranoia as the narrator.
Clearly the face of a reliable narrator.
The unreliable narrator is also a tool for constructing plot twists; what better way to leave the reader’s jaw hanging by revealing things that should have been plainly visible, but have been painstakingly hidden from the viewer’s eye? Sharin no Kuni, Himawari no Shoujo is one of those works — the unreliable narrator manages to deceive the reader by downplaying hints to the twist as minor eccentricities, then proceeds to hit the reader in the face (repeatedly, I may add) with all the hints given by the story when the twist is revealed. Note that hiding things and then revealing them out of the blue does not simply work; enough hints must be scattered throughout the story without being obvious — this is so that the twist does not come off as something pulled out of the writer’s ass at the last minute.
When the narrator is also a character in the story, their unreliability as an unbiased observer can be put to use as a character trait — a familiar example to most people on this site would by Kyon from the Haruhi Suzumiya series. Kyon narrates himself as a level-headed, objective person, but he keeps hiding his motivations and intentions from the reader. This characterizes him as a tsundere character for all the supernatural antics going around him, which then becomes a major point in the fourth novel.
Of course, the unreliability of the narrator can also hurt a story more than it can help. One of Agatha Christie’s novels is highly controversial for featuring an unreliable narrator, obfuscating several clues to the killer’s identity, but never outright lying about them. This led to Christie being accused of violating the rules of fair-play mystery; cries of how the novel’s solution wasn’t fair were thrown at Christie faster than Dlanor A. Knox can say, “<DIE THE DEATH!> <SENTENCE TO DEATH!> <GREAT EQUALIZER IS DEATH!>”
The unreliable narrator is a powerful tool for deception, something that shouldn’t be taken lightly. Deceiving the reader is something that a writer should not do, unless they know what they are doing. In the right hands, it can become a strong tool for hiding important things that the reader shouldn’t know and revealing them at the right time. Such is the power of deception, the power of the narration written not through the eyes of God, but an imperfect human.