Rei's Purpose is the 665th chapter of the Kingdom manga, written and illustrated by Yasuhisa Hara.
Synopsis
Rei's attitude during the push out of the forest gets out of hand, combined with her bloodthirstiness and mercilessness has taken a toll in the patience of the Hi Shin infantry. Kai reveals to Shin and Ten about Clan Shiyuu's ritual, and that six years ago, she killed Yuu Ren and hid her body. But she now believes that the elders most likely found out about Yuu Ren's death before continuing the ritual anew, that Rei was the eventual winner, and that Kai was her target all along.
Rei is alone and throwing up when Kou calls out to her. Suspicious, she notes that he used one of Kai's skills which produced a soundless step. Angry at his ignorance and offer to help, she points her sword at him, only releasing him when others call for him. With Kyou Rei's bloodlust resulting in even surrendered Zhao soldiers and restrained prisoners being killed wantonly, Suu Gen and the rest of the infantry leaders confront Shin over her callousness. While uncomfortable with her as well, Shin tells them to wait three more days for Kyou Kai to recover and pass judgment.
Unwilling to wait, an angry Suu Gen and the Hi Shin Unit confront her the next day and reprimed her uncontrollable actions. They demanded that she leave or be killed - with Suu Gen revealing they all know that she hurt Kou earlier. She confronts all of them, including Kan To, and dismisses them as weaklings to be slain or spared on a whim if they prostrate as an apology. She blows the cover of Sou brothers who were hiding nearby as she easily senses them and almost starts fighting with everyone. Immediately Kai appeared and told her to no lay a hand on the Hi Shin Unit as she knows Rei is aiming to kill Kai herself.