In Juuni Kokki (12 Kingdoms) Youko meets 2 other girls (near the end of the series). One of the girls (forgot her name - she was a supporting character) had worked for more than 100 years for a bitch of an imperial concubine (the concubine as well as all her servants were immortal) of sorts before she ran away.
Otherwise I'd go with Nana from Elfen Lied. Locked up and used for experiments to see what the physical possibilities of the diclonii are. Then Lucy.
Then maybe any of the girls from AIR, especially Kamio Misuzu who were basically dumped by her parents on her aunt who had to keep her distance. Sure, she wasn't physically tormented, but she was indeed alone and no-one dared to come close to her.