
Victorique is a mysterious girl who spends all her time at the top of the library in an exclusive boarding school in a small fictional European country called Sauville before WWII. Kujo, a Japanese student attending the boarding school, meets Victorique when he is given the task of taking her class assignments. He discovers that Victorique is a child genius with a mysterious past and joins her in solving mysteries with spooky themes, including murder, at this boarding school where everyone is obsessed with ghost stories. Some of the stories take place in the school itself, while others take place elsewhere.
As the series goes on, the premises of some of the stories get stranger. Kujo comes to realize pretty quickly that Victorique is actually a prisoner at the school as well as a student. Her father is a nobleman with a lust for power, and he is raising Victorique to use as a pawn in his rise to power. Victorique’s birth was part of a sinister plan that her father started before she was born. He plans to use the obsession the people of Sauville have with stories and legends, raising Victorique to play the role of a legendary figure to manipulate the feelings of the populace, unless she can find a way to escape her father’s schemes and find her own destiny. Even with her high intelligence, she will need Kujo’s help!

Although the series is set in the 1920s, many of the characters, especially Victorique, are wearing clothes that look Victorian. Victorique is shown as looking doll-like and wearing gothic lolita style clothes. Like Sherlock Holmes, she smokes a pipe.
This is not a series for young children! The dark stuff gets pretty dark, and the stories take weird twists. It is eventually revealed that Victorique’s father kidnapped and raped her mother to produce Victorique, thinking her exactly the sort of person who could have a daughter who would be right to play the part that he wants her to play. Victorique’s mother is from a mysterious isolated town of people known as the Gray Wolves, and there are many stories and legends about these people, which is why Victorique’s father targeted her. Victorique’s father has kept her hidden away from her mother since she was small, but Victorique dreams of reuniting with her. She secretly tries to help Victorique escape from her father. This series is best for teens and young adults.
Unfortunately, only two of the light novels were ever translated into English. The ones that were translated into English are not currently in print, and they’ve become collectors’ items, making them rather expensive to buy when you can find them on Amazon, Ebay, or similar services. From what I’ve seen, Ebay tends to have the most affordable copies. Apparently, the series wasn’t very popular in the United States, which is probably one of the reasons why I like it. I think, to fully appreciate this series, you have to know some things about classic mysteries, detectives, and ghost stories to get all of the references in the stories. The title is a take-off on the word “gothic” for the gothic genre, and the series includes many tropes from gothic literature. Victorique is like a combination of Sherlock Holmes and Nero Wolfe as a detective.
The light novels and manga are both available in other languages besides their original Japanese. I’ve especially noted German translations. I can’t read German, so I’m only going to cover the first two light novels in English. However, you don’t have to worry about starting a series you can’t finish because the entire series was made into an anime series, and that is available in English.
There is also a spin-off series with the same characters. The follow-up series is set in New York City in 1931, where Victorique and Kujo have created new lives for themselves after their adventures in Europe. Victorique has become a private detective, and she calls her business the Gray Wolf Detective Agency. Kujo is a newspaper reporter, and the stories he investigates frequently intertwine with Victorique’s investigations. Kujo and Victorique get married in 1934.
Light Novels:
Because only two of these books were translated into English, they are the only two I have listed here. To see the full list, I recommend this Light Novels Guide, which also lists books in the follow-up series.

Gosick: The Novel (2003)
Kujo and Victorique meet for the first time, and they solve a murder mystery aboard a terrifying ghost ship.
The Crime That Has No Name (2003)
Victorique reveals aspects of her past, and she and Kujo visit the town her mother was originally from. There, they learn that the reason Victorique’s mother left the town years ago was that she was suspected of a murder she did not commit. Victorique solves the murder and clears her mother’s name.