The Older Sister Spider Demon was a member of the Spider Family.
Her physical features are similar to that of her "Younger Brother" Rui, completely milky pale white skin complexion with snow white hair, her eyes are pure white with only her silvery pupils separating them from her sclera, she also possess several red dot like patterns in her face similar to her "Family". Her original appearance as a demon was completely different than her current, having morphed and changed her features due to being forced by Rui to be a family, her original appearance was simple,having black hair and slitted cat like eyes and grayish skin.
The Older Sister Spider demon is shown to be the most cautious of her "Family" having instead opted to observe and stand back rather than jump right into the battle against Demon Slayers, shes also shown to be one of the most cowardly of her family both with battling against the Demon Slayer Corps and dealing with the internal conflict of her "Family" as seen when the Mother Spider Demon was being violently abused and reprimanded by "Younger Brother" and her "Father" instead of helping her she instead opted to stand back and give her "Mother" the same severe glare due to her weakness, and she again showed her cowardice by trying to convince Rui to run instead to fight after most of their Family was defeated. In truth the Older Sister spider demon loathes and hates her "Family" and has begun thinking that she would have likely done better on her own and believes that the rest of her "Family" to be idiots for playing along with Rui, but non the less did whatever it took to survive she even went as far as attempting to use sympathy and pity on Shinobu Kocho despite knowing that she was a demon slayer, later also showing a more gullible side to herself when she genuinely believed Shinobu's promise not to kill her and got her to confess the amount of people she has killed.
(Source: Kimetsu no Yaiba Wiki)
