The Real World is the reality apart from the Universe of the Four Gods. Spanning decades, characters who make the trip inside the book are tethered to their lives in Japan.
In Fushigi Yuugi: Genbu Kaiden, Takiko Okuda grows up during the Taishō period (1912–1926). Suzuno Osugi's story in Fushigi Yuugi: Byakko Senki takes place almost immediately after the events of Genbu Kaiden in 1923 before picking up again during the Shōwa period (1926–1989). Meanwhile, the events of Fushigi Yuugi: The Mysterious Play with Miaka Yuki and Yui Hongo occur during the Heisei period (1989–2019).
While not explored as much in the anime as in the manga, there are a handful of prominent locations that make an appearance throughout the series.