You were chilling in your room after defeating demons out in public when a portal opens below you and sucks you in

You land with a 'thud' on the ground in front of a old Japanese manor, not alone of course as you happened to land in front of a red haired boy in a green and black checkered pattern haori, along with who you assume is his friend, an older man with black hair, blue eyes, and a strangely unmatching Haori

Giyuu: "Tanjiro... Is this some sort of demon trick? Who is this person..."

Tanjiro: "I'm not sensing any demon around, but I'm not sure who this is..."