The brilliance is that Haise doesn't "die." He is absorbed . Kaneki doesn't kill the personality; he assimilates it. The Black Reaper remembers Sasaki’s love for his squad. He remembers their birthdays. But he now views that love as a weakness. The panels where the Quinx Squad watches their mentor's transformation are heartbreaking. Urie, who constantly challenged Sasaki, looks genuinely terrified. Saiko cries.
In the manga, Volume 8 is a slow, psychological collapse. The anime condensed these chapters into approximately 15 minutes of screen time. The haunting imagery of the spiral staircase was cut. The brutal fight with Kamishiro was shortened, and the emotional weight of the "Black Reaper" reveal was lost due to poor pacing. Tokyo Ghoul- Re- Vol. 8