Maria Euphoria is the older sister to Jeanne Euphoria and another sibling. She is the current Empress of the Gran Chaos Empire and the first female to rule the empire.
Maria is described as the exact opposite to her sister Jeanne and Kazuya. She is idealistic and hopeful, though she is also described as slovenly by Jeanne and shown to be somewhat air-headed at times. Like Kazuya, she keeps a bed in her office.
(Source: How a Realist Hero Rebuilt the Kingdom Wiki)