Toshiko Sato's mother
Toshiko's mother was kidnapped by Milton and she forced Toshiko into makeing a sonic modulator in exchange for her mother's life but Milton used the sonic modulator against Toshiko and her mother but UNIT came in and arrested Milton and Toshiko. After her daughter agreed to work for Torchwood, Jack Harkness gave her an smnesia pill so that she never remembered that she was kidnapped. Later in her life, a vision of her (induced perhaps by Bilis Manger) enouraged Toash to turn against Jack with the rest of the team and open the rift. Her eventual fate is unknown. In both instances mother and daughter conversed in japanese.
She was played by Noriko Aida and she appeared in TW:End of Days and TW:Fragments.