Mary Saotome

Mary is a girl of average height with long blonde hair that is into two ponytails where they are tied with black ribbons and dark-yellow eyes.

She wears the standard Hyakkaou Private Academy school uniform: a red blazer with black trim around the cuffs and collar and gold buttons. Beneath the red blazer, she wears a white button-up shirt and black tie. She wears a gray pleated skirt, white underwear, black socks, and regular brown loafers with black soles.

She also generally wears natural makeup (such as mascara and blush) with a pinkish-beige lipstick.

At first, Mary is shown to be incredibly sadistic and twisted. One example of her personality is how she treats her classmate Ryota Suzui after he turned into a "housepet" due to his low social status within the academy. She is shown cruelly taunting her opponents during their gambling matches. She's also shown to be extremely egotistical both in and out of matches, often being confident in her victory. Mary also possesses a habit of mocking her opponents and laughing at them, especially when match seems to be her win.

After losing to Yumeko Jabami and experiencing the life of being a housepet, Mary, having no other goal in mind, became desperate to regain her status within the academy. Soon after being humiliated, Mary eventually loses her pride after she has a mental breakdown during a match against Yuriko Nishinotouin and falls into the state of grief and shame. After regaining her status, she seems to be no longer be as arrogant and cruel as before. Still, she is sometimes slightly nettled by Ryota's cowardice or Yumeko's reckless behavior; but she still cares deeply about them. She also developed a huge hatred towards the student council, and wished for them to pay for what they had done to housepets.

In Twin, it is revealed that her family isn't wealthy and she's attending Hyakkaou Private Academy on a scholarship. Her goal has always been to become a true winner in life, which is an important case even to her own parents, who were encouraging her from a young age to make friends with richer children. She takes a great pride in her intelligence and gambling skills, and she hates when people look down on her just because for her financial status. During the prequel, she is also noticeably less ruthless. Since Tsuzura Hanatemari is absent from the main story, Mary is shown to still keep her hairpin. She seems to be upset about whatever happened to her friend. Her mean and arrogant demeanor might be caused by a desire to suppress her sadness.