Mary is the late wife of George Joestar and mother of Jonathan Joestar. She accompanies her husband during a trip to London and dies protecting her baby when her carriage has an accident and falls off a cliff.
Mary has short curly light hair kept up to her neck. She wears a choker necklace with a locket along with a Victorian dress. Her dress is decorated with a rose.
At some point in the 1860s, Mary and George Joestar have a pair of rings made by a famous jeweler for their engagement. After they get married, they have a son named Jonathan Joestar on April 4, 1868. Shortly after Jonathan is born, Mary and George travel with him to an art gallery in London. George finds a Stone Mask there which he likes so Mary buys it for him.
On their way back home, their carriage slips off a cliff due to the rain and Mary dies in the accident, protecting her baby. Dario Brando sees their bodies and steals the wedding ring that Mary gave George. However, George actually survived and misunderstands the situation thinking Dario is saving them. Dario confirms Mary's death and George laments that he should have died instead of her, but is glad their son is safe.
George starts wearing the ring that he had given to Mary, but it is so small that he has to wear it on his little finger. Some time later, Dario tries selling the ring he stole from George and is arrested by the police. The Scotland Yard police officer confirms they found the famous jeweler who made the rings for Mary and George and he remembered the couple. George lies for Dario's sake and tells the police officer that he gave Dario the ring, hoping Dario would learn from the incident and become a good person.
George keeps the Stone Mask hung on a wall of his house as a memento of Mary. Jonathan also keeps a photo of Mary on top of his bed's headboard. After being bullied by Dio, Jonathan looks at the photo and cries, missing her.
In 1888, Jonathan studies how the Stone Mask functions, mentioning how the mask was originally obtained from his mother's travels. He feels a sense of longing to see her despite having no memories of her.