i love the headcanon that giyuu is a big brother to the kamado siblings. he was the first to believe in tanjirou and have faith in nezuko. he even went as far as to put his life on the line if nezuko ever ate a human. i just love the idea of giyuu taking care of the kamado's as if they were siblings. it makes me happy that they found each other and stayed connected for the rest of their lives, as if they really were siblings <3