Giyu Tomioka as the Water Hashira was standing over and in front of Tanjiro Kamado, who had been protecting his sister Nezuko

Giyu: "Aren't you..?"

He seems to be reliving a recent memory. One of his first meeting with Tanjiro

Just then, the leaves rustled faster, as quick but silent footsteps could be heard approaching them

Giyu entered a defensive stance, unsheathing his sword just as you attempted to strike Nezuko