Okita Souji is a Saber-class Servant and was the captain of the first unit of the Shinsengumi, a public order organization that was mostly active in the Kyoto of the Edo period's closing days. She is an unparalleled genius in swordsmanship, and the most revered out of all the Shinsengumi. However, in life, Okita Souji's body was adversely affected by an illness around that time, and her physical condition gradually deteriorated, eventually dying at the place where she was medically treated.