Maria is Nagi's maid and surrogate older sister/mother, and is the only one who understands the problem between Hayate and Nagi. She is the character with the most common sense in the series, and appears to be the one in charge of everything in Nagi's manor, since everyone from the head butler to the SP either obeys or fears her (or both in some cases). She's good at general housework and likes games of all kinds, though she is deathly afraid of cockroaches, which she refers to as "the dark life-form that exists in the kitchen and other places". She has also proved capable of self-defense techniques in times of need.
She has no last name because she was an orphan who was found next to the statue of St. Mary at a church, which is where she got her name. Not knowing anything about herself, her birthday was decided as December 24, the day she was found. She is the unfortunate one who always has to clean up everyone's messes. She has seen Hayate naked multiple times(and been seen naked by him once), and she sees the effect he has on other girls, many of whom are attracted to him for his kind nature. Eventually she, too, develops a crush on Hayate. Maria is also legendary throughout Hakuō Academy for having graduated high school at the age of thirteen in just three years while maintaining the position of Student Council President for all three years. Because of this she was able to recommend Hayate to Hakuō Academy despite him narrowly failing the entrance exams. Due to such unusual experiences, she both appears and acts in a manner more mature than people typical of her age. Because of this, even people near to her speak of her as if she is older than she really is, a pet peeve for her. She commonly responds back that she is still a fresh 17-year-old girl and remains 17 years old (according to this phrase) throughout the entire 16-month-span of the series. She may have met Athena as a baby. In the Animax-Asia version, which is dubbed in English by Red Angel Media, Maria is given an English accent.