The Master Key (大いなる幻影, Ōinaru gen'ei) is a 1962 novel by the Japanese novelist Masako Togawa which received the Edogawa Rampo Prize upon publication.
[1] The English translation by Simon Grove was first published by Dodd, Mead & Co in 1985.
[2] It is a mystery story set in the 1950's postwar Ikebukuro, Japan with the setting of K Apartment for Ladies, reserved only for women.
Many of the aging residents have their own secrets bound to the master key, which opens all of the 150 rooms in the K Apartment.
[3] All the secrets start to unravel when the building is slated for construction work to be moved four meters with the residents inside.