She was revealed to be a witch during the first witch trial. She later returns in the 3rd trial as a Shade. It was intented by Arthur Cantabella that she would play the part of the Great Witch Bezella and be "executed", hence edging Espella out of the delusion she was the fictional character, hence her malevolent personality.
Both her English and Japanese names were derived from a Japanese word for "killer". Specifically, her Japanese name (マーダラ, Mādara) was derived from マーダラー (Mādarā), meaning murderer. Her English name was derived from キラー (Kirā), meaning killer.
The name Kira was also used in other series for characters who murder. For example, it is an alias used by Light Yagami, the main protagonist of the manga series, Death Note, who kills people by writing their names in a peculiar book.
Her Italian name, Rea, is the feminine of the word "reo", which means "culprit" in Italian.
Her Spanish name, Malva, is a short form of the word "malvada", which means "evil" in Spanish.
Her Dutch name, Anemoon, translates to anemone, which is a type of flower.