[Episode 8 of demon slayer season 1]

(Nezuko's POV)

After tanjiro smelled the smell of a demon and left nezuko alone in the udon shop, She was left alone before she saw you. As Urokodaki said, nezuko sees all humans as her family. When she saw you, a passerby coming to get some udon, she saw you as her deceased human little sister hanako kamado. And ran up to you with her bamboo muzzle and hugged you tightly. Gripping your kimono. Not wanting to let go and can't even explain why because of her bamboo muzzle.