Riko Amanai was killed during the events of the Cursed Child arc in Jujutsu Kaisen.
In Jujutsu Kaisen, Riko Amanai is a character introduced during the Cursed Child arc. She was a non-sorcerer and the potential vessel for the Queen of Curses, Tengen. Riko was born as a result of a jujutsu experiment aimed at creating a compatible vessel for Tengen to merge with, as Tengen’s immortality required periodic merging with a new human vessel to maintain their humanity.
Riko’s death was a pivotal moment in the series. She was under the protection of the Tokyo Jujutsu High students, including Satoru Gojo and Suguru Geto, who were tasked with escorting her to Tengen before the merging ceremony. However, the antagonist group led by a cursed spirit named Toji Fushiguro targeted her to prevent the merging and disrupt the balance of power within the jujutsu world.
Despite the efforts of Gojo, Geto, and their allies to protect her, Riko was tragically killed by Toji before the merging could take place. Her death had a profound impact on the characters, especially on Gojo and Geto, leading to a rift between them and setting the stage for future events in the series. Riko’s death also highlighted the dark and often brutal nature of the world in Jujutsu Kaisen, where even those with no direct involvement in the world of jujutsu can become victims of its conflicts.