Toshiko Sato

}} is a fictional character from the television series ''Doctor Who'' and its spin-off ''Torchwood'', played by Naoko Mori. After a one-off appearance in the ''Doctor Who'' episode "Aliens of London" (2005), Toshiko is re-introduced as a series regular in the ''Torchwood'' premiere episode "Everything Changes" (2006). The character appears in every episode of the show's first two series as well as Expanded Universe material including ''Torchwood'' novels, audiobooks and comic strips.

Within the series narrative, Toshiko is the Cardiff branch of Torchwood's "technical expert", described as "quiet but highly intelligent", and a "computer genius". Aside from lead character Jack Harkness, she is the regular character with the longest history with the Torchwood Institute, having been recruited three years prior to the series. Her characterisation explores the differences between her nature and that of her colleagues and her difficulty in romantic relationships. A general backstory relating to her pre-Torchwood life and long-standing crush on colleague Owen Harper is hinted at across the first series, and explored more thoroughly in the second series. Mori departed the cast in the series two finale, "Exit Wounds" (2008). Provided by Wikipedia