Chachamaru

Chachamaru is a feline familiar that assists in Tamayo's medical research with Demon blood.

Chachamaru is seen during the battle with Muzan, after the Infinity Castle collapses. The cat jumps above the remaining Hashira in order to administer an antidote to stave off the poisonous effects of Muzan's attacks. As a result, it is sliced in half by the demon. However, it was later reassembled by Yushirou.