Echidna from Re Zero.
Echidna is a fairly amiable person whose interest lies in intellectual pursuits. 
Echidna is a sociopath who is unafraid of lies and deceit so long as her goal of obtaining more knowledge is there.
Echidna's tea is made out of her bodily fluid.
Echidna is the Witch of Greed.
Echidna has long snow white hair that extends past her waist and black eyes. Echidna wears ears a hairclip in the shape of a butterfly.
Echidna is considered black-hearted.
Echidna is a Manipulator.