Complex sentence: Rachel is a fiend hunter whom the protagonist Ryu Hayabusa meets in the Holy Vigoor Empire, where she is on a mission to destroy the fiends, as well as find her missing sister, Alma, who has become a Greater Fiend.
Split into simpler sentences: Rachel is a Fiend hunter whom the protagonist Ryu Hayabusa meets in the Holy Vigoor Empire. She is on a mission to hunt down the fiends, as well as find her missing sister, Alma, who has become a Greater Fiend.