After previously being dismissed by Rui, the Older Sister Spider Demon can be seen dashing through the forest in a panic. Her thoughts are jumbled as she tries to think of a plan in order to redeem herself as a member of the family. As a result, she reveals that the Spider Family were not related by blood, but were instead a coalition of frightened demons who agreed to join Rui's group for protection.
In order to be a member of the "family", their appearances were changed to look similar to Rui and they were violently punished when they failed to obey his commands. She also reveals that he would "cut them, steal their intelligence, or leave them to die from the sunlight" if they failed to fulfill their role as a member of the "family".
When the Demon Slayers defeated the Mother Spider Demon, the Sister Demon had tried to warn Rui so they could run to safety, but when doing so she revealed her original face which angered him.
As she continues to run through the forest, she encounters Murata and uses Blood Demon Art: Acid Cocoon to entrap him. He helplessly tries to slice through the silk, but the Older Sister Demon reveals that the material cannot be cut and he will soon be dissolved by her dissolution fluid to become her meal. In that instant, the Insect Hashira, Shinobu Kocho, stealthily appears behind the Older Sister Demon and inquires about the silk she had spun and calmly greets her. Shocked by her presence, the Older Sister Demon quickly emits more silk in order to capture Shinobu but fails to do so. However when Shinobu tries to initiate her counter attack, the Older Sister Demon tries to convince her otherwise.
In an effort to gain Shinobu's sympathy, the Demon reveals that she was forced to carry out her tasks by Rui, causing Shinobu to ask how many she's killed. She begins to cry and tearily reveals that she has killed only 5 people, but Shinobu calls her on her bluff and accuses her of killing more due to the cocoons she discovered in the forest. The Older Sister Demon asks why she wants the exact the number, to which Shinobu responds that she needs it in order to properly punish her. Shinobu explains the importance of atoning for ones sins in order to be reborn, and describes her explicit plan of gouging out the Older Sister Demon's eyes, cutting her stomach, and disemboweling her.
Enraged by her remarks, the Older Sister Demon emits her silk as an attempt to capture and kill the Hashira, but her efforts are stopped when Shinobu uses Insect Breathing: Butterfly Dance - Caprice to demobilize her. The Older Sister Demon grabs her neck to realize her head is still attached, but when she attempts to attack Shinobu a second time, her body begins to falter and she falls to the ground withering in pain.
Shinobu advises the Demon that she shouldn't let her guard down just because her head was still attached, warning that there are some Demon Slayers who use poison in combat. She formally introduces herself as the only Hashira who cannot decapitate Demons, but utilizes poisons instead.
She then cheekily apologizes for speaking to the Older Sister Spider Demon, after she had already died from the poison.
Characters in Order of Appearance
- Older Sister Spider Demon
- Father Spider Demon
- Older Brother Spider Demon
- Mother Spider Demon
- Shinobu Kocho
- Shinobu Kocho defeats the Older Sister Spider Demon