Also known as: ガラスの靴
A pair of shoes made out of glass, based off of the Cinderella (Fairy Tale) fairy tale where the heroine wears such a pair of shoes to the royal ball, but must flee at midnight and accidentally leaves one behind. The prince uses the remaining shoe to identify Cinderella, since it can only fit her feet.
Despite being called 'slippers', they are actually High Heels.