Pia (ピア) is a Cyborg child assasin formerly a member of the Social Welfare Agency. Pia is a rogue cyborg whose handler, Earnest, is working with the Five Republics Faction. Her ingame dialogue states that she was created at the same time as Henrietta and Rico.
The only appearance of Pia is the GSG PS2 games that come with the Season 1 anime Volumes 1-4 only available in Japan. Pia and Earnest never appaear in the manga or anime and they are never mentioned either. Pia's weapons of choice are the IMI Desert Eagle and the Armalite M-16A1 with an M203 40mm grenadelauncher.