Fushigi Yûgi

While visiting the National Library, junior-high students Miaka Yuuki and Yui Hongo are transported into the world of a mysterious book set in ancient China, "The Universe of The Four Gods." Miaka suddenly finds herself with the responsibility of being the priestess of Suzaku, and must find all of her celestial warriors for the purpose of summoning Suzaku for three wishes; however, the enemy nation of the god Seiryuu has manipulated Yui into becoming the priestess of Seiryuu. (myanimelist.net)