Fushigi Yûgi has been in and out of publication since 1995.  The original series, Fushigi Yûgi: The Mysterious Play, is one I've previously reviewed.  There is also another series, Genbu Kaiden, that came out after the original, but not one I have had the chance to get my hands on.  Genbu is a prequel to the original series.  Byakko Senki is set after Genbu and before the original, but you don’t really have to read any of the others in order to understand this story. This book makes reference to Genbu, but Watase explains all you need to know.

Suzuno is a sweet, ten-year-old child who loves her parents very dearly, growing up in 1920s Tokyo. Her father has a book, The Universe of the Four Gods, that he forbids Suzu from touching. Then, the Kantō earthquake of 1923 strikes and destroys her home. Suzu’s father tells her to open the book in order to save her, and she is transported into the book to the country of Xi-Lang. There she meets Ning-lan, a woman who can turn into a tiger. Later, Ning-Lan and Suzu meet brothers Karm and Kasal, who tell Suzu the legend of the Priestess of Byakko. When Ning-Lan turns on Suzu, Suzu is transported back to Japan, and is immediately beset upon by human traffickers. She is rescued by a boy named Seiji and Dr. Oikawa, a friend of her father’s, but she loses the book in the process. A significant time jump occurs. Suzu is in high school, struggling with dreams and slivers of memories from losing her family to being attacked by a tiger. Seiji joins the military in hopes of establishing a life for himself, and while an injury ends his military aspirations, he asks Dr. Oikawa for Suzu’s hand in marriage.

​Fushigi Yūgi is a shōjō, and it was originally released from 1992-1996 and has been re-released several times.  It is another classic Isekai following the adventures of Miaka and Yui.  The two young ladies begin their adventure in a library, and the reading of a book transports them back to Feudal China.  Yui manages to escape back to the "real" world rather quickly, but Miaka finds herself the Priestess of the god Suzaku, tasked with gathering the seven celestial warriors in order to summon the god.  She ends up falling in love with Tamahome, one of the seven warriors.  Yui, meanwhile, works diligently to retrieve her friend Miaka, only to come back into the world of the book and find Miaka in love and seemingly unmoved by her disappearance.  Jealous and outraged, Yui becomes the Priestess of Seiyū, gathers her own warriors, and declares she will do everything to stop Miaka from summoning her god.