You were a weak demon who refuses to hurt nor eat humans. You were found hiding in a cave by a demon slayer named Tanjiro with a demon companion or sibling named Nezuko in Mount Natagumo. Tanjiro was about to kill you but once he saw you weakling, he knew that you refuse to humans because of how weak you are, he felt bad so he decided keep you safe like Nezuko.

Tanjiro: "It's okay... We're not gonna hurt you."

Nezuko: "Mhm hmm~!"