Tomoyo Daidouji is a fictional, major supporting character in Clamp's anime and manga series CardcaptorSakura. Tomoyo is the best friend of the series' protagonist, Sakura Kinomoto, and her second cousin on their mothers' sides.
In the Japanese version, she is voiced by the famous voice actress, Junko Iwao.
In the English version, she is first voiced by Maggie Blue O'Hara in Cardcaptors, Michelle Ruff (second voice), who also voices Rukia Kuchiki and Sinon, in Card Captor Sakura the Movie 2:The Sealed Card, and Natalie Hoover (third voice), who also voices Sonia Nevermind, in the Clear Card Arc in the English Version.
Tomoyo is an elegant and delicate-looking young girl with porcelain-white skin and long, wavy, grayish-violet hair, which is very similar to that of Sakura's mother, Nadeshiko Kinomoto. It was later revealed that Tomoyo's own mother, Sonomi Daidouji, had made her grow her hair like that so she would look like Nadeshiko. She also has purple eyes, making her and Sakura the only two people to have an eye colour other than brown or gray from her other classmates (excluding Eriol).
Tomoyo is the best friend of the series heroine, Sakura Kinomoto. When she discovers that Sakura has become the Cardcaptor, she becomes Sakura's primary assistant by designing "battle costumes" (similar to another CLAMP character, Hokuto Sumeragi, who designs extravagant outfits for herself and her twin Subaru) and filming all of her magical (and non-magical) endeavours. (The videotaping, however, seems to be more to Tomoyo's personal benefit and enjoyment than it is to Sakura's.) Tomoyo faithfully keeps Sakura's new identity secret and often covers for her in times of need.
In the early releases of the manga, one of the artists was not aware that Tomoyo had feelings for Sakura. As a result, some scenes in the beginning chapters show Tomoyo with a slight crush on Sakura's brother Toya. Clamp soon clarified the story with each other, however, and Tomoyo is subsequently seen showing more attention towards Sakura.
Tomoyo is the daughter of the president of Daidouji Toy Company, Sonomi Daidouji is the cousin of Sakura's mother Nadeshiko Kinomoto, which makes Sakura, Toya and Tomoyo second cousins. Tomoyo's father is never shown in the series and is only alluded to once, but it is apparent that he does not live in the Daidouji household. Her western-style house in Tomoeda is quite grand, with several maids serving the household. She is sometimes attended by the Daidouji family's team of female bodyguards, and has access to prototype technology from her mother's company (including the cell phones she supplies to Sakura and her circle).
Tomoyo is very mature for her age. One of her major character traits is her selflessness towards Sakura. Tomoyo is kind, caring, sweet, highly intelligent, beautiful, meticulous, and very melodic (she has a superb singing voice and often has solos in choir recitals). She enjoys making costumes for Sakura to wear and filming her all the time. She also sings in a club at school. Tomoyo can be slightly over the top at times (only where Sakura is concerned), but otherwise she is practically perfect in every way. She always speaks using formal verb conjugations and expressions, giving her a unique air of refinement amongst the cast. When needed, Tomoyo can exhibit considerable cunning and resourcefulness, which was most prominently displayed in the final movie (much of which revolved around a complicated scheme she had devised to give Sakura as many opportunities as possible to confess her feelings to Syaoran).
Tomoyo aids Sakura's efforts to be in the company of Yukito Tsukishiro on many occasions, and, in the second half of the series, becomes the confidante of Syaoran Li when he finds himself falling in love with Sakura.
The daughter of the president of Daidouji Toy Company, Sonomi Daidouji, Tomoyo lives a life of wealth and is watched over by a team of female bodyguards. She has access to a variety of prototype technological gadgets from her mother's company, and supplies Sakura and Kero with different communication devices throughout the series. She is depicted as being mature, kind-hearted, intelligent, and regularly speaking using more formal verb conjugations and expressions than normally seen in elementary students. She is a talented singer, and is shown performing in various school events. In the anime, her musical ability causes her to be targeted by both the Voice and Song cards.
When she learns of Sakura's new role as a Cardcaptor, she insists that Sakura must wear "special outfits" and begins providing Sakura with the various costumes she wears during her captures as well as accompanying her on missions to record the events with her video camera. In the manga, some scenes give the appearance that Tomoyo has a crush on Sakura's brother Toya; however, according to an interview in the Cardcaptor Sakura Memorial Book, this was an error caused by one of the finishing artists not being aware that CLAMP intended for Tomoyo to have feelings for Sakura. In future volumes, this is corrected by having a scene note that Tomoyo blushed around Toya because he reminded her of Sakura. While Tomoyo is in love with Sakura, she notes that she is happy to be able to be with Sakura and does not require Sakura to love her back. Instead, she encourages Sakura's love of Yukito, and later becomes Li Syaoran's confidant and ally when he falls in love with Sakura. The familiar relationship with Sakura is removed and all dialog suggesting that she has romantic feelings for Sakura are edited to be purely platonic in nature.