Takaishi Natsuko--otherwise known as Nancy Takaishi--is the divorced mother of two Chosen Children, Ishida Yamato and Takaishi Takeru. She and Takeru live together; in Digimon Adventure in an unspecified part of Tokyo, and in Digimon Adventure 02 in the Tokyo Bay area of Odaiba, Japan. She is a journalist who has written a number of resources on the Digimon incidents that took place in 1995 and 1999.

Natsuko was formerly married to Ishida Hiroaki. He has been referred to as Ishida Masaharu in fancanon in the past, according to Megchan, because during the run of Adventure there was a peice of Japanese fanart where the artist named him Masaharu, and it mistakenly spread to the English fans. Hiroaki works for Fuji Television, a real television network based out of Odaiba (all five Digimon series were broadcast by Fuji) which is the setting for numerous encounters in the first two seasons.

Natsuko is blonde with blue eyes, characteristics her sons have also inherited. After they separated, she and Yamato don't see each other often (it is revealed in one of the drama CDs that Yamato chose to go with his father because he believed Takeru needed a mother's care more), and there is some tension when they interact at first. Natsuko's appearances are usually alongside Takeru rather than Yamato. However, Natsuko leaves the safety of their home to accompany Takeru to Odaiba during Vamdemon's attack with almost no hesitation, and Yamato refers fondly to his mother at a point in 02, so it is possible that after the events of Digimon Adventure they may have become closer.

Natsuko and Hiroaki act strangely for a divorced couple. They are seen holding hands at one point, and although they seem nervous around each other, it is clear there is still something between them. No confirmation was ever made in the series about the reason for their separation, but it is likely based on the cultural perception of women pursuing careers after marriage, or Hiroaki's tendency to overwork, possibly both. Their attitudes toward each other (Natsuko still calls him by the pronoun "anata", which is commonly used by wives for their husbands) are friendly and even seem to hint at a real possibility of still being in love. However, not much abouut their relationship is explored during the series.

In Digimon Adventure Natsuko is portrayed as being overprotective of Takeru, who is 8 years old at the time. By the events of 02, they are living in Odaiba, and seem to enjoy a friendly relationship. Like Hiroaki, Natsuko's work clearly means a lot to her, and she is seen in the first episode apologizing for not being able to accompany Takeru to school. Her line of work, however, affords her a chance to help the Chosen Children out as her husband did in the first season; it is Natsuko who reports her meeting with Oikawa to Takeru, and later she obtains the names of the children infected by the Dark Seed. Hiroaki makes an appearance in 02 as well, turning a blind eye to the "camping trip" the children went on to cover for their absence while battling the Digimon Kaiser.

With the exception of Koushirou's parents, both Natsuko and Hiroaki are seen more than many of the other families. They are the non-Chosen that appear the most often in both Adventure and 02 and play a more significant role than most of the other adults in the series.

In the Japanese version of the show, Natsuko is voiced by Sakamoto Chika (who also provided the voices of Agumon and Lillymon). Barbara Goodson plays her in the English dub. Hiroaki is voiced by Hirata Hiroaki and David Greenlee, respectively.