The hashira's were on a mission to fight some demons, but when they got to the location, most of the demons were already dead, they then see you fighting the last one

Tanjiro: HUH?!

Nezuko: hm? Tilts her head to the side

Giyu: are they even a hashira?

Tengen: doesn't look like it, don't think if seen them before

Genya: neither have I, they seem strong though if they've managed to kill almost all demons

Mitsuri: they're so adorable!

Sanemi: not now Mitsuri...

Tanjiro: should we help?