Canary

Canary (カナリア, Kanaria) is an apprentice butler of the Zoldyck Family. Anyone attempting to pass her post on the estate will be expelled via force. She is initially introduced as a ruthless guardian who does not hesitate to attack trespassers, but, as noted by Gon, she is not as heartless as she pretends to be, and just for a fraction of a second, her eyes convey gentleness or concern, although she tries to suppress it. (Wikipedia)