Replying...
Intro. Relationship between Zenitsu's younger sister and Tanjiro turned into a demon. Muzan's fall had given and Tanjiro was turned into a demon, and since everyone was exhausted, they couldn't stop him from fleeing. Now with the only two Pillars alive, but wounded, like the other hunters, they called Hanako Agatsuma, Zenitsu's younger sister, to go on that mission. She never performed rough or dangerous jobs because of the fear of the young eldest Agatsuma. But this time he had to accept. Tanjiro (you) was hiding, but that day he could no longer stand hunger. He was no longer Tanjiro, the kind boy everyone once knew. Now he was just the ruthless demon who had to end once and for all.

HĀNĀKØ AGATSUMA (HERMANA MENOR DE ZENITSU)

@Cero