Jeri Katou

Jeri Katou (加藤 樹莉, Katō Juri) is another Tamer and one of Takato's classmates. She's also one of Luna's best friends and she always has a sock puuppet with her.

Before Digital Dawn (Digimon Tamers)
At first, Jeri is not very important to the series. She just plays as a school girl Takato has a crush on and won't become a Digimon tamer until later on. It might be said that she is a sort of perfect child, because of her cheerful and happy personality. However, there was a scene when she had claimed she was not interested in digimon, but had cards dropping out of her pocket when she fell. She was known for her dog-shaped sock puppet from her brother, which she uses to strike-up conversations.

Where Kazu and Kenta ran away when the existence of Guilmon (Takato's partner Digimon) was proven, Jeri was quick to befriend the strange digital life-form, becoming the first non-Tamer to do so.

Jeri is into the DigiBattle Card Game and has some very rare cards in her possession. Takato's friend Rika Nonaka gave her some pointers on what cards to use, and that is how the friendship between the two of them got started. Jeri becomes a Tamer and her partner is Leomon, although when he first appeared, she didn't exactly show that and rather chased him like a madwoman, calling him her Prince and looking almost starstruck at the sight of him. She eventually becomes Leomon's partner before she and the other Tamers (including Kazu and Kenta) headed out into the Digital World in search of Calumon.

Jeri proves herself to be a very capable Tamer with potential for greatness (she used the extremely powerful and rare LadyDevimon card on Leomon to destroy the evil digimon Orochimon who had kidnapped her), but unfortunately her career is cut short when Beelzemon destroys Leomon and uploads his data.

Following this Jeri becomes withdrawn, believing that her destiny is to be alone. Some time during their return to the real world, Jeri 's cheerful facade is ripped away and through flashbacks and a brief explanation she delivered to Takato, her less-than-cheerful past is revealed. Her biological mother had died a while ago and when Jeri met her stepmother, she didn't give her a chance, as she was still very deeply traumatized by her mother's death. Following this Jeri began to think she was a bad person because she knew her stepmother was a nice woman, but still she was unable to accept her, she couldn't empathize with her. She also thinks over and over about the words that her father said after her mother's death, which Leomon repeated before dying: "it's all because of Destiny."

Jeri showed no sign of caring about what was going on around her and she kept on looking into her now dead D-Arc. The only real reaction came when Takato and Guilmon, now fused into Gallantmon, were about to kill Beelzemon after defeating him; she yelled at them to spare him, and when Beelzemon asked her why, she tearfully said she didn't want anyone else to die because of her. When she disappeared for a moment and then came back, her eyes were different, as if something possessed her, and she had an evil smile, even after the kids were back in Tokyo.

We later discovered that this was not Jeri rather it was the D-Reaper's Agent 1, by discovering its "wings", who assumed Jeri's form to learn all she could about the Tamers. The real Jeri had been taken away and placed in a space within the D-Reaper. The Agent 1 said that Jeri was the perfect being for the D-Reaper as it used her sadness to strengthen itself. During this time, Calumon somehow sensed her presence and made an attempt to rescue her along with Impmon, who after wallowing in guilt for what he did to Jeri became determined to save her. Impmon digivolved to Beelzemon Blast Mode to defeat a bunch of Bubbles Agents and managed to open a hole big enough in the Kernel Sphere (the place she was trapped in) for Calumon to enter but was captured himself. He was eventually released and thanks to Gallantmon and Grani who managed to defeat the Agent guarding the Sphere, tried desperately to break Jeri free from her prison. He finally broke through by using Leomon's Fist of the Beast King (he was able to do so thanks to having absorbed his data). Unfortunately this had an adverse effect, as it was a harsh reminder to Jeri that Leomon was dead and that the perpetrator who caused that was right in front of her, and thus, terrified, she backed away from her would be savior. In the urgency of the situation, Jeri did eventually accept Beezlemon's good intentions, but alas she reached out to him too late; before she could grab his hand Beezlemon was attacked and plummeted to the ground, and the Sphere closed up again, trapping her along with Calumon

Meanwhile, Jeri's puppet was being controlled by the D-reaper and it was trying to convince Jeri that humans don't deserve to live. D-Reaper was able to feed off her negative emotions, but gradually, thanks to Calumon she decided to speak up and reject the idea of real death. She spoke what Leomon had spoke (while he was destined to die, she still had a lot to live for, and so did the others) and was rescued by Takato after the D-Reaper was defeated. During the battle Gallantmon and then Gallantmon Crimson Mode attempted to reach the Kernel Sphere and rescue her. Gallantmon Crimson Mode defeated and destroyed many Agents in his attempt to rescue her including the immensly powerful Jeri Type Agent. During this time Jeri managed to break the Kernel Sphere with her D-Ark but it began to become flooded with Chaos Mass. Calumon somehow protected them with a forcefield and got them out of the Kernel Sphere. Gallantmon Crimson Mode reached the Sphere but she wasn't there but nearby but before he could reach her he de-digivolved into Takato and Guilmon. Takato finally rescued her by having Guilmon fling him to her with his tail.

By the end of the series, Jeri snaps out her depression, thanks to Takato and Calumon, and realizes that humans can make their own destiny and that she was never meant to be alone.

During the D-Reaper Saga Calumon seemed to become a sort of second partner to her coming to her rescue with Beelzemon, cheering her up and protecting her somehow with a forcefield during the final battle before Takato managed to rescue her. Also when everyone said their goodbyes to their partners at the end, Calumon was the one she said goodbye to, thanking him for helping her out.