Nancy Takaishi (高石 奈津子 Takaishi Natsuko?) is the mother of Yamato "Matt" Ishida and Takeru "T.K." Takaishi. She and the father, Hiroaki Ishida, divorced when the boys were still young. Nancy lives with T.K., and only sees Matt when he comes by to pick T.K. up.
Nancy is kind and friendly. She is a loving mother to T.K. and her warmness is reflected in his own cheerful personality, whereas Matt is more reserved and stubborn as a result of not growing up around his mother. Nancy doesn't feel that she has a strong connection with Matt any more which causes tension between them when they meet. She is very protective of both of her sons and does not wish for them to fight in case something happens to them. She is very supportive of both T.K. and Matt and their responsibilities as Digi-Destineds. 
Nancy was once married to Hiroaki Ishida, with whom she had two boys, Matt and T.K. However, the two divorced when the children were still young, with Hiroaki retaining custody of Matt while Nancy retained custody of T.K. Since the divorce she and Matt maintained little contact which caused an awkward relationship to develop between the pair of them. Matt is especially cold and is shown to shun her when she greets him warmly in episode 39. This may be due to Matt feeling angry and blaming her for the divorce that split up the family, or perhaps simply because he didn't want to betray his father who he is especially close to.
Nancy works as a journalist and after her and Hiroaki's divorce she moved away to Sangenjaya, taking a young T.K. with her. During the Myotismon saga she and T.K. watch the events that are happening in Odaiba unfold on television from their apartment. T.K. is determined to go to Odaiba and help his friends fight and Nancy agrees to take him there. When the children return to the digital world in episode 39 she is shown to be particularly upset at having to say goodbye to her two sons. She is reluctant to let T.K. leave but allowed it after being encouraged by her ex-husband to let their sons go and fight.
During the final battle Apocalymon she is seen with the rest of the Digi-Destined's families watching on from Earth supporting them. She is shown to be holding hands with Hiroaki at this point, hinting that there is perhaps still some feelings of love between them.
By the time of Digimon Adventure 02 she and T.K. have moved back to Odaiba and she appears to have a much better relationship with Matt.
Notes and references
|Main characters:||Taichi "Tai" Kamiya | Yamato "Matt" Ishida | Sora Takenouchi | Koushiro "Izzy" Izumi | Mimi Tachikawa | Joe Kido | Takeru "T.K." Takaishi | Kari Kamiya|
|Digimon:||Agumon | Gabumon | Biyomon | Tentomon | Palmon | Gomamon | Patamon | Gatomon|
|Villains:||Devimon | Etemon | Myotismon and DemiDevimon | Dark Masters | Apocalymon | Diaboromon | Millenniummon|
|Other characters:||Gennai | Willis, Gummymon, and Kokomon | Ryo Akiyama | Koromon | Leomon | Ogremon | Wizardmon | Other characters|
|Relationships:||Taichi "Tai" Kamiya | Yamato "Matt" Ishida | Sora Takenouchi | Koushiro "Izzy" Izumi | Mimi Tachikawa | Joe Kido | Takeru "T.K." Takaishi | Kari Kamiya|
|Other media:||Digimon: The Movie | Digimon Adventure | Our War Game! | Digimon Grandprix! | Character Song + Mini Drama 1 (2, 3) | 2½ Year Break | Anode and Cathode Tamer | Novel | Albums | PSP game|
|See also:||Digimon | Digital World | Digivice | Crests | Black Gear | Dark Network | Peace Keeper | List of episodes|