The story begins at the luxurious Kogetsukan Hotel. You arrive there for what was meant to be a four-day, three-night stay. A threatening letter delivered to the hotel turns out to be deadly serious when a guest is murdered. As one of the characters drawn into this, you find yourself on a quest to uncover the culprit. What truth will come to light during your seven-day investigation?
A murder mystery-themed event in Fate/Grand Order. It was guest-written by Madoi Ban and later adapted into a novel illustrated by Yamanaka Kotetsu.
In it, Fujimaru Ritsuka has a dream where they witness a murder case unfold between a meeting of two crime families. All the characters in it are portrayed by servants Ritsuka is contracted to, due to their brain filling in missing details. Sherlock Holmes, James Moriarty (Archer), and Mash Kyrielight end up helping guide Ritsuka to solving the mystery.
Member of the Goldie family. The patriarch of the family and the father of Morris and Lorie, with Dorthy as his second wife. Had affairs with both Harriet and Ann, and is the true father of Juliet, Eva, and Chris.
Father of the Violet family, who married into the family and took on their last name. While Cain is his legitimate son, when he married Harriet she was pregnant with Aaron's children, though this isn't public knowledge and the two are legally recognized as his children.
Member of the Violet family. Because she's represented by Raikou, Ritsuka mistakes her for being Adamska's wife, but she is actually Juliet's younger twin sister. She's the daughter of Aaron and Harriet from an affair, with Adamska as her legal father.
Member of the Violet family. Attends college with Rikka, and is the reason they were at the meeting of the Goldie and Violet families. Eldest daughter of Adamska and Harriet, with Eva being her younger twin sister. Correctly guessed by players as the true culprit behind the murders.
Member of the Violet family. Because she's represented by Euryale, Ritsuka mistakes her for being Juliet's sister, but she's actually Juliet & Eva's mother. She became pregnant with twins after an affair with Aaron, marrying Adamska and having them legally recognized as their children. Cain is her youngest child.
Member of the Marble trading company and a long-time business partner of Aaron Goldie. The mother of Chris, who she had from an affair with Aaron, though she kept his parentage secret, not recognizing him as her son.
Member of the Marble trading company, with Ann as his primary caretaker. Is actually Ann's son, born from a one-time affair with Aaron, though he's unaware of his parentage.
A college student who was invited to the island by their friend Juliet. Portrayed in the novel as a cross-dressing womanblondelook-alike for the male Ritsuka, who attended as Juliet's pretend boyfriend in order to ward off advances from Morris.
Believed by Ritsuka to be someone identified as having the appearance of Holmes like the others, but is actually Holmes himself taking on a false role.
