Taisho Era refers to the Japanese history era when Takiko Okuda was inside The Universe of the Four Gods, and the summoning of the beast god Genbu along with the tragic death of the priestess. It's also the time when the first chapters of Fushigi Yuugi: Byakko Senki took place; the rest of Suzuno Osugi's story happens during the Showa Era.

The Taisho era in itself is named after Emperor Taisho (personal name: Yoshihito), father of Emperor Showa aka Hirohito (the one reigning during Suzuno aka Byakko no Miko's adventures) and grandfather of Emperor Heisei aka Akihito (reigning when Miaka and Yui are priestesses of Suzaku and Seiryuu, respectively). It goes between July of 1912 and December of 1926 and it's regarded as the "Taisho Democracy", relatively liberal compared with the conflicted Meiji Restoration and especially in comparison with the extreme militarization of the first part of the Showa era, leading to Japan's role in World War Two.