|Sylvia Mercury First|
|Full Name||Sylvia Mercury First|
|Occupation||Warrant Officer (Stars)|
|Ability Name||Voice Transmission|
|Novel||Volume 9, Chapter 2|
Sylvia warms up towards Lina easily, as to follow the order of disclosing Lina's identity during their missions and simply because of her personality.
Sylvia is the closest person with Lina during their missions in Japan. She also lives in a high class condo with Lina as a roommate, while acting as her support personnel. Lina easily interacts with her as she displays an older-sister-like character towards her.
Lina is sad when Sylvia has to return to their nation in order to examine and ensure that her body free from the Paranormal Parasite's infection.