Jeri would often weird Takato out in school by talking with a sock puppet. At one point she noticed Calumon's shadow and tried to sneak up on him "like a lion" (foreshadowing what was to come). Takato at one point considered Jeri for Calumon's tamer, but thought she would freak out. When she asked him to show her Guilmon, Takato did even though he thought she would freak out, but instead she thought he was cute, and after the battle with Mihiramon, would hang out with him in the park along with Kazu and Kenta.
At one point Jeri decided to become a tamer. She initially wanted Calumon as her tamer, but when Kumbhiramon attacked them, he revealed to her that he does not fight. Then Leomon fought Kumbhiramon off, and Jeri chased after him, believing him to be her partner. As she did not have a digivice, the only reasons for this was that she thought it was destiny. After Kumbhiramon returned and was destroyed by Leomon, he left, and Jeri was disappointed that Leomon was not her partner.
However, after being attacked by Makuramon, Jeri did become Leomon's tamer, as she received a digivice. They traveled with Takato and the others to the digital world to rescue Calumon, who had been kidnapped by Makuramon.
They traveled to the Forgotten Village, a warped up area, and the forest area, where Jeri, who worked in a restaurant, was captured by Orochimon, who forced her to make milkshakes for him. She made as many as she could to tire him out for the battle, but the data in the milkshakes made him stronger. When Orochimon gained the upper hand, Jeri felt responsible, but later used a LadyDevimon card on Leomon enabling him to destroy Orochimon.
After arriving in the Land of the Sovereign, Leomon was destroyed by Beelzemon. Before dying, he told Jeri that she had a lion's heart and part of him would always be with her. Jeri fell into depression because of this, but told Gallantmon to spare Beelzemon when he was at his mercy, saying she didn't want anyone else to be hurt because of her and that killing him wouldn't bring Leomon back. This caused Beelzemon to feel regret for the first time.
After they rescued Calumon from the D-Reaper, Jeri walked away, saying sadness could be deleted. It is presumed that she attempted suicide by jumping into the chaos pit. She was not destroyed, but held inside the D-Reaper's brain, with the D-Reaper feeding off her sadness and disguising an agent as her to accompany the tamers back to Earth, where the D-Reaper followed.
Calumon and Beelzemon tried to save Jeri, but Calumon became trapped with her inside the D-Reaper's brain. Beelzemon used Leomon's Fist of the Beast King (aided by Leomon's spirit) to punch a hole in the brain, but Jeri became depressed seeing it was Beelzemon and not Leomon, and by the time she accepted his help, the hole had closed up. Beelzemon was attacked by the D-Reaper shortly after, and Jeri presumed him dead.
Eventually Jeri fought back against the D-Reaper, realizing it twisted her memory of Leomon into something ugly, and Leomon's spirit blew up part of the D-Reaper's head. Calumon projected a barrier around himself and Jeri, and as the D-Reaper was being sucked to its doom, Guilmon threw Takato at Jeri with his tail and he got to her, from which they and the other tamers and Digimon were saved from the void by Kazu, Kenta, and MarineAngemon.
Jeri saw for the first time that Impmon survived the D-Reaper's attack, and forgave him for killing Leomon. After the Digimon's return to the digital world and return to Earth, Jeri was often seen with Calumon, and attended Rika's birthday party.