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Sylvia Mercury First (シルヴィア・マーキュリー・ファースト) is a Planetary-Class Magician who serves in the USNA's Magician Unit "Stars". She holds the rank of Warrant Officer. Her code name is Sylvia Mercury First, whereas her nickname is "Sylvie". 
Appearance and Personality
Sylvia possesses an unrestrained personality, where she can easily forget things such as differences in rank. 
Sylvia is 25 years old as of January 2096. 
Besides her first name, "Sylvia", the rest are code names, which identify her to be ranked first among the Planetary-Class "Mercury" of Stars. She is a highly regarded female CO who attained the title of "First" at an early age. 
In the beginning, Sylvia didn't want to join the military and intended to become a journalist after graduating from college. She has an outstanding ability in data analysis. 
She is a magician specializing in intelligence gathering. During the Visitor Arc, and the Prologue of Disturbance Arc, she was sent to Japan to gather intelligence on Japan's undisclosed Strategic-Class Magician that was responsible for Scorched Halloween.