『瑠璃城』殺人事件

1989, Japan: A corpse in a locked library. 1243, France: 6 knights suddenly vanishing from a castle. 1918, Battle of Verdun: 4 corpses vanishing from the front. And endless cycle of impossible crime situations and the predestined demise of 2 lovers.

『ギロチン城』殺人事件

Self-proclaimed detective Makube Nako finds a doll disposed on 'doll mound' that writes the message "Help" with a photo attached, that shows a girl standing in front of a guillotine. This indirect client leads Nako and his friend Yorishina Yuuki to the legendary Guillotine Castle, a place that stores numerous execution tools and is equipped with an excessive security system. One year ago, the castle's lord was found decapitated in a locked room situation with a decapitated Russian doll beside him. After Nako and his companion arrive, Guillotine Castle welcomes them with another locked room murder...

『アリス・ミラー城』殺人事件

Various detectives are gathered on Erikajima to investigate Alice Mirror Castle and find the Alice Mirror. A chess board with 10 white figures makes the detectives aware of their situation being strikingly similar to a certain literary masterpiece and the further development unfortunately supports their hunches...

『クロック城』殺人事件

In 1994 a sunspot 30 times as huge as the earth was discovered and by its influence the planet has been in disorder since then. The world is said to meet its demise in 1999. It is in that year, that a certain request for detective Minami Miki drops in. He proceeds to Clock Castle, whose outer wall is furnished with 3 huge clocks which display past, present and future, and whose interior is divided into 3 separate mansions as well. The proprietor's daughter, Kurou Ruka, is said to be Midnight's Key, a crucial being in earth's final moment. She asks Miki to investigate the eerie face staring out of the cellar's wall. Ruka suspects a ghost called Skipman, which rumor has been passed on in the mansion for generations. This Skipman is supposed to be able to rip a hole into time and travel into the past and future. Soon after Miki begins his investigations, a seemingly impossible murder resembling the legend of Skipman ensues...