Jeri Katou

Jeri Kato, known in Japan as Juri Kato (加藤樹莉 Katō Juri), is a fictional character from the Digimon Tamers series.

Usually shown with her sock puppet early on in the series, Jeri is a cheerful person who is always there to encourage her friends. It is also hinted that Takato Matsuki has a crush on her, and by the end it is obvious that the feeling is mutual. This, however, shows the love-triangle in the series since Takato also had a slight crush on Rika Nonaka.

Digimon Tamers, 1st Half
At first, Jeri is not all that important in the begining. She just plays as a school girl Takato has a crush on. You might say that she is perfect because of her cheerful and happy personality.(She didn't become a digimon tamer untill later on) 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 sock puppet from her brother, which she uses to strike-up on 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. Rika 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 madman. But, she went to the Digital World with the others.

She eventually becomes Leomon's partner before the Tamers (including Kazu and Kenta) headed out into the Digital World in search of Calumon.

Digimon Tamers, 2nd Half
Jeri proves herself to be a capable Tamer but unfortunately, her career is cut short when Beelzemon kills Leomon and loads 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Following this Jeri becomes withdrawn, believing that her destiny is to be alone.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 becomes the puppet of the D-Reaper. Her cheerful facade is ripped away and through flashbacks, her less-than-cheerful past is revealed. It seems that her mother had died a while ago and when Jeri met her stepmother, she didn't respect her very well. To Jeri, she didn't give her new mother a chance.

Jeri showed no signs of caring about what was going on around her and she kept on looking into her now dead D-Arc. When she disappeared for a moment and then came back, her eyes were different as if she was possessed by something, and she had this evil smile on her face.

We later discovered that this was not Jeri rather it was the D-Reaper's Agent 1, by discovering it's "wings", who assumed Jeri's form to learn all she could about the Tamers. The real Jeri had been taken away and placed 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.

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. We don't know if Jeri agreed on this (probably not) and later, Jeri decided to finally speak up. She spoke what Leomon had spoke and soon was rescued by the other tamers.

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

Digimon Tamers: Runaway Digimon Express
Jeri not only attended Rika's birthday, but she along with Calumon also helped Rika's Grandmother, Seiko Hata with all the decorations as well.