Laplace no Ma is a mysterious, humanoid figure with the head of a white rabbit who appears in the N-field, the dreamlike realm that connects the Rozen Maiden dolls. He wears a formal tuxedo and a top hat, giving him a somewhat theatrical appearance. His name is a reference to a famous philosophical concept, the Laplace demon, an all-knowing intelligence. In the story, he functions as an observer and referee of the Alice Game, the contest among the Rozen Maidens to become the perfect girl. He often approaches the dolls or their human masters to offer cryptic, riddle-like advice or to guide them toward important encounters. His words are poetic and seemingly nonsensical, yet they frequently carry meaningful hints about the nature of the game or the dolls' personal struggles.

Laplace no Ma is neither clearly benevolent nor malevolent; he remains detached and ambiguous throughout the series. He speaks in a composed, enigmatic manner and rarely reveals his own intentions. Though he is sometimes seen in the company of antagonists such as Barasuishou and later Kirakishou, his true motives are never fully explained. He is the true form of a character named Shirosaki, a white rabbit who appears earlier in the story. His presence is felt even before the events of the second season, as he was already searching for the Rozen Maidens before the rivalry between Shinku and Suigintou began. Despite his occasional assistance, he never commits to any side, maintaining an air of neutrality that leaves the other characters and the audience uncertain of his ultimate goal. His ability to traverse the N-field freely and to appear and disappear at will makes him an enigmatic guide who influences the course of the Alice Game without directly participating in it.