Okita Souji, the captain of the Shinsengumi's First Unit, whose name resounded through Kyoto in the Bakumatsu period.
Historically, she left her name behind as a man, but in this world, she appears to have been a woman.
As in history, she has a weak constitution, and when she receives a shock or becomes exhausted, she coughs up blood. She suffered from pulmonary tuberculosis and passed away young, and because of that, she deeply regrets not being able to fight alongside her Shinsengumi comrades to the very end. The wish she entrusts to the Holy Grail is "to fight through to the end." To that end, she had considered having the Holy Grail remove her troublesome "Weak Constitution" skill, but in "FGO," it was declared that even the Holy Grail cannot do that. What a shame.
"My weak constitution can be cured? Yay! Huh? My skill as a Heroic Spirit can't be cured? But you said my wish would come true! Waaah!" โ From her My Room voice line about her wish for the Holy Grail
Incidentally, her hair color is a pinkish blonde... or rather, white hair.
She calls you "you-san."