A mask that you can use with your anime avatar, was made for the more rounder faces, but it can be scaled to fit others. Comes with a blank texture with shading but can be replaced with anything you want. (Just 45 Degree it to make it line up correctly)
In your scene go down your avatars Armature until you get to the head and just drag it there from your project assets :) You will have to adjust it there but it should move with your head and whatnot.