Tomoyo is the best friend of the series heroine, Sakura Kinomoto (Sakura Avalon in Cardcaptors). When she discovers that Sakura has become the Cardcaptor, she becomes Sakura's primary assistant by designing "battle costumes" 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.