Toshiko Sato

Toshiko "Tosh" Sato|佐藤トシ子|Sato Toshiko in Japanese. is a fictional character from the television series Doctor Who and Torchwood, played by Naoko Mori. She is a regular in the latter programme for the first two series, but actually first appeared in the Doctor Who episode "Aliens of London". In Torchwood, Sato is the Cardiff branch's "technical expert", described as "quiet but highly intelligent", and a "computer genius".

Television
Sato first appears in the Doctor Who episode "Aliens of London", credited as 'Doctor Sato', when she is called in to examine a supposed alien corpse at Albion Hospital. Although it is not mentioned in the episode that she is working for Torchwood Three, it is later revealed in Torchwood episode "Exit Wounds" that Sato was deceptively standing in as a medic to cover up for a hungover and unreachable Owen Harper.

We are reintroduced to Toshiko in the Torchwood premiere episode "Everything Changes". In "Greeks Bearing Gifts", Toshiko enters into a sexual relationship with a woman named Mary, from whom Toshiko receives a telepathy-granting necklace. Her experiences with telepathy greatly distress Toshiko. She expresses despair and hopelessness, noting that across space, all cultures are essentially similar, leading to utter disappointment with existence.

In episode "To the Last Man", Tosh has a relationship with a soldier from 1918, who had to be frozen and re-awoken every year until the time was right for him to return to 1918 and heal the rift. In episode "Reset" Owen agrees to go on a date with her, but dies at the end of the episode after being shot in the heart. When Owen is briefly revived by Jack using a resurrection glove, Tosh says her goodbye to him by confessing that she has always loved him. Owen flatlines, only to revive again permanently, existing in a state resembling undeath.

In the show's second season finale, "Exit Wounds", Toshiko is shot and killed by Gray, Jack Harkness's unstable younger brother. She dies within minutes of Owen, having been unable to save him from his own death when he becomes trapped in a nuclear power facility bunker flooding with radioactive material. In the moments before their deaths, Owen apologises to Toshiko for never having managed to bring their relationship to full fruition. By initiating the final log-off procedure for her account on the Torchwood computer system, Ianto activates a pre recorded message from Toshiko, in which she thanks Jack for saving her. She tells him that she is grateful for the opportunity to work in Torchwood and see all the wonders she'd seen, and that she loves them all. After being killed off, the character is referenced in several episodes. In the two episodes of Doctor Who which follow "Exit Wounds", Gwen and Ianto vow to keep fighting in Tosh and Owen's memory, and later discover a "time lock" designed by Tosh which protects the Hub from Dalek invasion.

Literature
Toshiko appears in the first six of the Torchwood novels, published by BBC Books. The first wave, Another Life by Peter Anghelides, Border Princes by Dan Abnett, and Slow Decay by Andy Lane, were published in January 2007 and form a loose story arc.

Published in March 2008, and tying in with the concurrently airing second series of Torchwood, Toshiko appears in the novels Trace Memory by David Llewellyn, The Twilight Streets by Gary Russell, and Something in the Water by Trevor Baxendale.

Toshiko also appears in the first two Torchwood audio books, Everyone Says Hello by Dan Abnett, narrated by Burn Gorman (who plays Owen), and Hidden by Steven Savile, narrated by Naoko Mori.

The novel Trace Memory depicts a five year old Toshiko living in Japan with her parents and elderly grandmother. This depiction is consistent with the character's history seeded across the series, although as with all Doctor Who and Torchwood spin-off media, the canonicity in relation to the television series is open to interpretation.

Character development
It is revealed in episode "Greeks Bearing Gifts" that Sato's parents were both in the Royal Air Force, and her grandfather worked at Bletchley Park, the World War II code-breaking facility. Sato joined a government scientific think-tank after graduating from university, and is recruited by the Torchwood Institute to work with Jack Harkness three years before the series begins. The episode "Fragments" depicts more fully the story of how Toshiko joined Torchwood; she is forced to steal the design plans for a "sonic modulator" from the Ministry of Defence, trading the finished design and prototype to an unnamed terrorist organisation in exchange for the freedom of her kidnapped mother. Captured by UNIT and imprisoned with an indefinite sentence and suspended human rights, she is later given a chance to escape captivity by Jack, in exchange for working for him as part of Torchwood Three for a minimum period of five years.

Toshiko has a close relationship with colleague Owen Harper throughout the series. Mori suggested in an early interview that Sato has a crush on Harper, also indicating that Toshiko has good working relationships with the rest of the team and in particular with Jack Harkness, although she is not afraid of expressing her opinions to him.

The Sun newspaper had claimed all the members of Torchwood were bisexual. Toshiko's own bisexuality is evidenced in episode "Greeks Bearing Gifts", when she begins a brief relationship with a female. Torchwood's second series explores other sides to Tosh's personality, romances, her crush on Owen, and sheds some light on her original Doctor Who appearance.

Speaking of the decision to kill off her character, Naoko Mori has commented that it "made sense because Tosh has been through so much. She's come a full circle and had her journey." With regards her input on the death itself, she stated: "One of the things that I wanted to ensure was that it made sense, and that the connection between Owen and Tosh had the right balance. All through the series I didn't want it to come across as her being this stalker girl with a crush on Owen. I wanted it to be deeper than that, because as a colleague and as a human being she cared for him. I wanted their last conversation to be delicately and well put." Mori has not ruled out the possibility of returning to the show at a later date.