Aria was a girl from the capital that offered Tatsumi a place to stay when she found him on the streets after being conned by Leone. She came from a wealthy family and had a habit of offering strays a place to stay in her mansion. Apparently, she and her family had an interest of luring people from the country to their place and tortured them to death.Night Raid killed her family, and Aria was killed by Tatsumi after he witnessed the death of his two friends, Sayo and Ieyasu, at the hands of Aria's family. (Source: Akame ga Kill! Wiki)