Mary is a key character in the horror adventure game and anime adaptation 'Ib.' She appears to be a cheerful and innocent girl who meets the protagonist, Ib, in the mysterious art gallery. Despite her friendly demeanor, Mary harbors a dark secret related to the world they are trapped in. As the story progresses, her true nature and connection to the gallery are revealed, making her both an ally and a potential antagonist, depending on the player's choices.