Trapped in a Loving Prison

Disclaimer: This is my first story, so it might not be very good
Warning: There will be smut
SPOILER WARNING: this story is based on events from the manga I recommend reading the manga first before reading this

Tanjiro is done selling coal and is on his way back home when the old man at the edge of the village warns him of demons. Tanjiro ignores his warning and heads home when he sees the corpses of his family and a large man clad in black clothing, Kibutsuji Muzan.