After being imprisoned by UNIT for assisting criminals under duress, Tosh was released by Jack Harkness under the condition that she work for Torchwood for five years. She was quiet and unassuming, generally using her computer genius to avoid exposure and to assist her colleagues. Nonetheless, she proved herself to be a field agent capable of taking on her own missions and projects. She had feelings for Owen Harper that she did not make known to him for quite some time.
Tosh was born in London in July 1975. In 1977, her mother and father, who had both been in the RAF, moved with her to Osaka (TV: Greeks Bearing Gifts; AUDIO: torchwood_cascade_CDRIP.tor) where they lived with her grandmother. Her parents taught her English. As a child, her favourite programme was Science Ninja Team Gatchaman. (PROSE: Trace Memory) She had a brother who died and whose death she felt responsible for, believing that she had abandoned him. (AUDIO: torchwood_cascade_CDRIP.tor) Their grandfather had worked at Bletchley Park. (TV: Greeks Bearing Gifts)
Whilst living in Osaka, Tosh was read fairy tales about Sentaro. At the age of five, she met Michael Bellini, who had time travelled into her bedroom, and was threatened by a Vondrax before Bellini left. (PROSE: Trace Memory) She was a big fan of Steve Ross's comic books, (AUDIO: Believe) was obsessed with Tetris (AUDIO: Zone 10) and was part of her school's Maths Club. (TV: Adam) In 1986, the Satos returned to the United Kingdom. (TV: Greeks Bearing Gifts)
When Tosh moved into her own flat, she chose not to have a flat-warming party as there was nobody that she wanted to invite. (TV: Adam) She got a job at the Ministry of Defence's Lodmoor Research Facility. (TV: Fragments)
Career at Torchwood
Tosh was blackmailed by Milton, who had taken her mother hostage, into stealing the Ministry of Defence's plans for a sonic modulator and building one. She managed to do so, improving upon the design as the plans were incorrect, hence their being shelved. Shortly after handing it over, Tosh was arrested by UNIT and held indefinitely and without hope of a trial or appeal. She did not know her mother's fate as UNIT refused to give her any information.
After some time, Tosh was visited by Jack Harkness who told her that her mother was okay and that Tosh would be held at UNIT forever to make an example of her. He promised her her freedom in return for five years' work at Torchwood Three, an offer that she took. (TV: Fragments)
Tosh worked alongside Jack and Suzie Costello, with whom she was temporarily frozen in a time bubble in the Hub for a day on the orders of Yvonne Hartman, who remarked that she was "cute". (AUDIO: One Rule) She attempted to find out Jack's identity, finding that there had been no US citizen by that name for fifty years. (TV: Day One) She developed feelings for Tommy Brockless, whom they unfroze once a day every year. (TV: To the Last Man)
They were joined by Owen Harper and Ianto Jones. (TV: Fragments) From the moment that Owen joined Torchwood, Tosh had to step in to save him, including posing as a doctor during his second week due to a hangover (TV: Fragments) to perform an autopsy on the Space Pig, which injured her, at Albion Hospital. She met the Ninth Doctor who told her the truth about the pig. (TV: Aliens of London)
Although Tosh considered new recruit Sebastian Vaughan to be a friend, he was unkind and sometimes racist to her, telling her that the team found her and her obsession with technology boring and that there was no real difference between the Chinese and the Japanese.
Tosh investigated the cortex leeches, which Sebastian told her was obsessive and unnecessary. They attacked Sebastian, who asked Tosh to kill him and told her that she was and would always be unsuited to Torchwood after she refused. Tosh took his body to Madeline Vaughan at Rockfell Hall, blaming herself for his death, and saved Madeline from Sebastian's leech-possessed corpse. (AUDIO: The Vigil)
Joined by Gwen
When Torchwood went to a crime scene to test the resurrection gauntlet, Tosh was the one to ask questions but ran out of things to say when the revived murder victim revealed he hadn’t seen his killer. She covered up the killing of a hospital porter by a Weevil by planting a false alibi and changing the hospital's rota, something that she told Gwen Cooper when she entered the Hub, telling her that it was her job to do so. (TV: Everything Changes) She was more sympathetic to Gwen on her first day than her colleagues and helped defeat the Sex Gas that had possessed Carys Fletcher, cornering it at the Conway Clinic. (TV: Day One)
Tosh helped Jack, Owen and Gwen track down the quantum transducer that Bernie Harris had in his possession, tracking him down and visiting his mother. (TV: Ghost Machine) She also helped to defeat the Bruydac, (PROSE: Another Life) Scotus and his alien tapeworms (PROSE: Slow Decay) and Lisa Hallett, whom she shot whilst she was in Annie Botchwell's body. (TV: Cyberwoman) She provided her teammates with valuable information on the Fairies (TV: Small Worlds) and the CARU Clinic. (AUDIO: Hidden)
She joined the team on a visit to the Brecon Beacons to solve a number of disappearances. In Brynblaidd, she and Ianto were kidnapped by the cannibals as part of the harvest. They were rescued by Jack. (TV: Countrycide) She had nightmares about the ordeal afterwards. (AUDIO: Broken)
Tosh had a brief relationship with the Arcateenian known as Mary, who tried to use her to gain access to her technology that Torchwood had confiscated. Their relationship was the first one that Tosh had had with another woman. To drive a wedge between her and her teammates, Mary gave Tosh a telepathy pendant, giving her an insight into others’ thoughts. She used this ability to foil a murder, by hearing the killer planning his attack in his mind and lied to the police that she’d overheard him mumbling about it. Eventually she agreed to take Mary inside Torchwood, but the team were waiting. Jack revealed Mary had been murdering men for decades but handed over her transporter when she threatened Tosh. Mary activated it, however Jack revised he’d tricked her as he’d reprogrammed it to take her into the Sun, to Tosh’s horror. Afterwards she spoke with Jack outside the Hub and chose to destroy the pendant for fear of its possible uses. (TV: Greeks Bearing Gifts)
Upset by what she had heard what her colleagues thought of her, she attended one of Simon's therapy sessions and became suspicious of him after Jolly Otter suffered an aneurysm after an argument with him. She employed Janet's help to stop him. (AUDIO: Instant Karma)
In 2007, (AUDIO: The Torchwood Archive) whilst working on a time lock in the Hub, Tosh solved the mystery of the Pulse's message ("Toshiko Sato. The truth is in Zone 10") and headed to Russia to look into it, escorted by Maxim Ivanov of the KVI. She learnt what he knew about the Committee and was given Object 1 by Anna Volokova, who sent the message as she escaped Zone 10 in her rocket. (AUDIO: Zone 10) Back in Cardiff, she reverse-engineered the locket to give good luck and had a "perfect day" in which Owen kissed her. After two days of this luck she came to the verdict that nobody should have that power, breaking her enhancements and sending Object 1 into the Rift. She confessed recent events to a bartender, having put retcon in her drinks to remove her memories of Object 1. (AUDIO: The Torchwood Archive)
On Jack's orders, Tosh destroyed the resurrection gauntlet to kill Suzie and save Gwen. (TV: They Keep Killing Suzie) She believed that Eugene Jones's death was a simple road accident so didn’t help Gwen’s investigation. (TV: Random Shoes) She supplied Diane Holmes, John Ellis and Emma-Louise Cowell with proof that they had time travelled and new identities so they could live in the present day. (TV: Out of Time) During Torchwood’s investigation of a Weevil fight club, she provided Owen with a cover story and identity to fool Mark Lynch. (TV: Combat)
Tosh joined Jack in visiting the the Ritz at 11 Richmond Street and was transported back to 1941, meaning that she missed her grandfather's birthday in London. She tried to get a complete equation to Gwen, Owen and Ianto in the future and failed to do so, but was able to return after Owen opened the Rift without them. (TV: Captain Jack Harkness) During the ensuing crisis, she accompanied Owen to a hospital where they discussed the Black Death had begun spreading in the present day. There she was tempted to open the Rift further by a vision of her mother and later joined Gwen, Owen and Ianto in rebelling against Jack to do so, unwittingly unleashing Abaddon. (TV: End of Days)
Following Jack's disappearance, Tosh was made team leader under Torchwood guidelines which assigned the role to the longest-standing member. However, she was temporarily rendered mentally unfit to command after exposure to an alien artefact and deferred command to Gwen. (PROSE: Kaleidoscope)
After Jack's return
Whilst dealing with a hostage situation involving a Blowfish, Jack returned and shot him. When Captain Joh Hart arrived Tosh admitted to finding him cute and helped locate the canisters that he claimed contained radiation bombs. She paired up with Owen to find one but they were ambushed by John, who shot Owen. Tosh treated him and they were found by Ianto. They then saved Gwen after John poisoned her and returned to the Hub to confront him. (TV: Kiss Kiss Bang Bang) She controlled the mind probe to interrogate Beth Halloran and uncovered Cell 114's plan to use nuclear warheads. (TV: Sleeper)
When Tommy was woken up, Tosh went out with him and, after they learnt that he had to go back to 1918, took him to her house where they slept together. When the Rift activity began, she encouraged him to return to resolve it despite knowing that he would be court martialled, knowing that it was the right thing to do. When Tommy was too shocked to activate the Rift key, Torchwood sent Tosh via a psychic projection to him to get him to seal the Rift breach behind him. (TV: To the Last Man)
Tosh helped investigate the Cash Cow and was the first to bring up the option of "putting it out of its misery". (TV: Meat) She and Owen were kidnapped by Bilis Manger and possessed by the Dark before he transferred it into Idris Hopper. (PROSE: The Twilight Streets) Thanks to Adam Smith's influence, Tosh became confident and believed herself to be in a relationship with him. She drew her gun when Adam was locked away but eventually resigned herself to taking retcon to forget and defeat him. (TV: Adam)
Finally mustering the courage, Tosh asked Owen out on a date. She was personally responsible for shutting down the Pharm and was devastated when Owen was shot and killed by Aaron Copley, (TV: Reset) confessing her love for him when they brought him back, for what she assumed would be the briefest of times, using the second resurrection gauntlet. (TV: Dead Man Walking) She still maintained hope of a relationship with him despite his being dead and wanted to help him deal with the situation. (TV: A Day in the Death)
As part of Owen's mission against the Church of the Outsiders, Tosh was tasked with seducing Frank Layton in order to search his house for information on the Church. She forced Owen to listen to her having sex with him as revenge for making her do it, although she was angry with herself as well as at him. When Frank began to suspect her of being a spy, Owen intervened and shot him dead, to Tosh’s horror. They discovered Frank had been guilty of nothing save financial dealing to help the Church avoid taxes, infuriating her that the evening had been a complete waste. On their way back to Cardiff, they were astonished when Jack appeared on a Church broadcast displaying his immortality and rushed to aid Gwen from Greys who had infiltrated the Hub. (AUDIO: Believe)
She used her computer skills to look into the Night Travellers (TV: From Out of the Rain) and helped Gwen collect information on people who had been taken by the Rift, theorising negative Rift spikes indicated abductions. (TV: Adrift)
Tosh was contacted by Stephen Heinz, formerly of Torchwood One, and travelled to London to help him solve a spate of disappearances. She discovered that the victims had all shared the same birthday and that a computer virus was to blame, trapping it in her Torchwood profile after changing her birthday in the records. (AUDIO: torchwood_cascade_CDRIP.tor)
Tosh joined the team, minus Gwen, in investigating Rift activity at an old building where they were caught in an explosion engineered by Gray and John Hart. After being rescued by Gwen and Rhys, she was left with a broken arm (TV: Fragments) for which Owen gave her painkillers so she could assist the team when John started attacking Cardiff. Tosh worked with Owen from the Hub to prevent Turnmill Nuclear Power Station from going into meltdown and destroying Cardiff. She was shot by Gray but continued to direct Owen, not letting him know that she was dying. After Owen failed to escape, he and Tosh disussed the date that they had never gone on and reminisced about their early days together. She heard Owen die and died in Jack's arms after he returned with Gwen, Ianto and John. She told them how she had failed to save Owen.
As the team deleted Tosh's profile on the computer system, an automated video message she had recorded played. In it, Tosh thanked Jack for saving her life and proclaimed her love for Owen and the rest of the team. She reassured them that it was okay that she was gone, saying that she hoped that she had done good. (TV: Exit Wounds)
Though dead, Tosh's presence was still felt by the others. When faced with certain death at the hands of the Daleks, who were about to overrun the Hub, Gwen expressed her desire to "go out fighting, like Owen, like Tosh"; (TV: The Stolen Earth) she and Ianto were saved by a time-lock defence system that Tosh had been working on before her death. The Hub was sealed in a time bubble, preventing a Dalek from entering to finish them off. (TV: Journey's End)
After the 456 incident, Jack revealed that he felt responsible for Tosh's death, along with those of all the other Torchwood operatives who had died under his command. (TV: Children of Earth: Day Five)
In an alternate timeline in which John Hart took control of the Torchwood Institute and became King of the British Empire, Tosh was likewise a member of Torchwood Cardiff, but died before Gwen Cooper was recruited by the king, who recalled that her death was "very sad, and messy and painful to watch" before agreeing to never speak of it again with Ianto Jones. Nevertheless, Ianto visibly burst into tears as John decided that Gwen would inherit Tosh's desk. (AUDIO: The Death of Captain Jack)
Tosh considered herself to be a rationalist. (PROSE: Slow Decay) She was a computer genius and arguably the most intelligent member of the Torchwood team. Despite her intelligence, she was insecure and not very confident in her abilities.[additional sources needed] She didn't like to be studied. She could complete a Rubik's cube within a minute, even when Owen peeled off and replaced several of the stickers. (PROSE: Another Life)
Sebastian Vaughan said that Tosh was spineless and did not listen to her instincts, saying that she was not and never would be Torchwood material. Tosh took notice of this and decided to trust her gut more. (AUDIO: The Vigil)
Tosh was in love with Owen Harper but because of her insecurity, she found it hard to tell him how she felt. (TV: Greeks Bearing Gifts) Tragically, both Tosh and Owen were killed before they could get into a romantic relationship. (TV: Reset, Dead Man Walking, A Day in the Death, Exit Wounds)
Toshiko worried Jack. While she was at the heart of the Torchwood team, she didn't realise it. She felt more remote. Jack suspected that beneath her reserved exterior, there was a supernova of emotion which he didn't want to damage the team. (PROSE: Slow Decay)
Behind the scenes
The series 1 version of the Torchwood website had correspondence from Tosh in an unsent draft sent to her aunt discovered by Ianto. It was translated from Japanese into English by Ianto. It said that "for the last week", Tosh was with a woman, referring to Mary, "going from a schoolgirl crush on Owen through to a fantastically fulfilling sex life with a complete stranger". She called it "a week of firsts", including: Tosh's first one night stand, lesbian kiss, lesbian "shag", and the first time Tosh was late to work because of sex.
- During her first on-screen appearances, in Aliens of London, Tosh was a pathologist called in to autopsy an "alien pilot". When reintroduced in Torchwood, she was a computer specialist. In her final appearance (Exit Wounds), the character would explain this discrepancy by explaining she was filling in for Owen, pretending to be an MD because Owen had a hangover.
- Tosh left a resounding impression in the Torchwood universe and in the final episode of Children of Earth Jack admits that he feels responsible for her death. It is assumed her body was destroyed when the Hub was blown up by a bomb.
- The name Toshiko means "genius child".
- Toshiko was the only known member of Torchwood Three other than Jack Harkness to have met an incarnation of the Doctor. Gwen and Ianto had spoken to the Tenth Doctor through the Sub-Wave Network during Journey's End, but Tosh was the only one to have physically met an incarnation of him.