迷路館の殺人

Prominent mystery writer Miyagaki Youtarou invites his 4 disciples, a literary critic, an editor and his wife and mystery maniac Shimada Kiyoshi to his underground labyrinth mansion. However he is found dead when they arrive and a tape tells his disciples of his wish to improve their skills under the condition of being locked into this closed circle situation and write themselves into their works using his mansion as location. Their works are to be evaluated by the critic and the editor and the winner is going to inherit Miyagaki's entire fortune. The authors begin to write their individual stories and it does not take long until murders happen according to those scripts.

This incident became fairly known afterwards and one year later a literary reconstruction published by Kitansha Novels arrives at Shimada's. It was written under the pen name Shishiya Kadomi, who claims to have been involved in the case, which Shimada acknowledges before he delves into the book...

笑わない数学者

Saikawa and Moe are invited to legendary mathematician Tennouji Shouzou's Christmas party in his mansion Mitsuboshikan. While the guests are in the mansion's planetarium, the huge Orion statue in front of the mansion vanishes and the professor challenges his guests to solve this mystery. When the statue appears again later, the corpse of a guest who was supposed to have been in her room is found in front of it, while another corpse turns up in her room...

翼ある闇 メルカトル鮎最後の事件

When the detective Kisarazu Yuuya and his companion and mystery writer Kouzuki Sanetomo arrive at the medieval-ish mansion Souajou, Kisarazu's client has already been killed, just as this client's son, with their heads being cut off and swapped with one body and head found in a locked room. For what sake do the serial murders in the Imakagami family continue? Why all the incomprehensible staging of the murders? And why was Kisarazu hired in the first place?