Peek-a-Boo Glasses can be used to see what kinds of hearts have crystallized within humans, witches and ogres. This is how Chocolat, Vanilla and anyone else from the magical world; are able to peek at the colour and presence of any hearts in range and extract them. By holding up two pairs of spread fingers to their eye(s) - it allows people from the magical world, to see the hearts in the chests of people an those hailing from Le Royaume. Peek-a-Boo Glasses were first introduced in the first episode in the anime.