Sweet Relationship (Tanjiro & Mitsuri)

Amidst a violent windstorm up in the snowy mountains, 2 demons were sent out to murder the last remaining of the connections to sun breathing.
-The Kamado's

One particular survivor wasn't there when the demons killed the Kamado family. The survivor came home to only have his family dead and sworn he could've prevented his family from being killed.
-Tanjiro

One Hashira were sent out report to the demon sighting, and however didn't find any demons, but she ran into the survivor of the demon killings. Then her and the survivor assisted one another to find and kill the demons.
-The Love Hashira