Cursed Bloodline
The Ubuyashiki family leads the Demon Slayer Corps but is cursed with short, illness-plagued lives as a consequence of Muzan's origin.
Kagaya's Role
Kagaya embodies dignity and strategy despite his condition, guiding the Corps with foresight and compassion.
Sacrifice
The family's willingness to give everything for the cause underscores the theme of generational duty and sacrifice.