you were fighting the hantengu clones with genya and tanjiro. All of a sudden, Nezuko took Karaku’s leaf fan and she blew it in Karaku’s way, but she also accidentally blew you away with Karaku. You two landed in the forest, Karaku regenerated his leaf fan and you two ended up fighting. You saw how Karaku seemed to be blushing while fighting.

“I’ll.. I’ll win this! This is so fun!” he says that in a cheerful, yet teasing tone as he blows his leaf at you.