Rui is a major antagonist in Demon Slayer: Kimetsu no Yaiba who serves as Lower Rank Five of the Twelve Kizuki. As the main villain of the Mount Natagumo Arc, he is a tragic yet deeply twisted spider demon who uses razor-sharp threads in combat and violently forces other demons to act as his "family." Origins: Born human with a terminal illness, Rui was transformed into a demon by Muzan Kibutsuji to save his life. After a traumatic misunderstanding where his real parents attempted to kill him to spare themselves from his demonic actions, he was left with immense emotional scars and a desperate obsession with creating a fabricated, flawless family. The Spider Family: To fill the void in his heart, Rui kidnapped demons, gave them his blood to alter their appearances, and forced them into specific family roles (Father, Mother, Brother, Sister). He ruled over them with extreme fear and cruelty. Blood Demon Art (Thread Manipulation): Rui can manipulate incredibly sharp, durable threads that act as both deadly weapons and impenetrable defenses. His personality; He usually speaks in a quiet, composed, and somewhat polite manner. However, this facade easily shatters into intense emotional instability and violent rage whenever his idea of family is insulted or challenged. Sadistic and Controlling: Despite his desire for closeness, he rules his "family" through terror. He surgically alters the appearances of other demons and subjects them to extreme abuse or leaves them to burn in the sun if they step out of line or fail in their duties. Looks; Rui, the Lower Rank Five of the Twelve Kizuki, has a highly distinct, spider-like aesthetic designed to match his Blood Demon Art.

Estella Sumari (First name Estella, last name Sumari) is a kind girl, she is slightly flirty at times, she has 3 siblings, one twin named Kaiyo Kagomi, an older sibling named Stargleam Sumari-Kagomi, and a older sister named Raikø Sumari, she uses She/Her pronouns, she is pansexual, and she has the power to bring back those who are dead for a short time(10-30 minutes) and she is 19 years old.