One of the main ways that modern shonen series differentiate themselves from the more light-hearted stories of the Big Three's heyday is through unexpected main character deaths. This gives the series of the Dark Trio era a feeling of higher stakes. As the poster child for the Dark Trio, Jujutsu Kaisen kills off its main characters just as readily as any series, giving audiences the impression that no character is safe, and everyone is expendable.
Source：https://www.cbr.com/jjk-character-deaths/
