Cathy Katherine, known simply as Cathy (キャッシー, Kyasshī) in the manga and Japanese version and nicknamed Cat (Cat-chan in the manga and Japanese version), is a supporting character appearing in Yu-Gi-Oh! ZEXAL and one of Yuma's friends. She has an obsession with cats to the extent that she behaves like them and can control them.
Cathy, like her nickname implies, has the appearance of a cat. She has two pieces of her gray hair held up by clips which give her the appearance of having cat ears. She has large and expressive green eyes which appear to have no eyebrows. She also wears the same outfit that Tori Meadows wears as they attend the same junior high school (in the dub, her skirt is lengthened). She also wears a pair of large, square-framed glasses. She also has a pink Duel Gazer with a purple lens that she wears with her glasses off, in contrast to Flip, whose Duel Gazer is directly integrated into his glasses.
When attending social events such as the WDC party, Cathy wears a Chinese style dress, which like most of her other outfits, sports cat like features such as a tail and gloves with the appearance of cat paws and claws. During the Heartland Academy festival, she wore a "Cat Girl" cosplay.
Cathy is a loner and a stereotypical shy girl, especially towards her crush; Yuma Tsukumo. However, she has shown to have a strong distaste towards dogs (when Pip tried to ask the gang for forgiveness, she brushed it off and displayed much anger, calling them "thieving Dogs!"). As stated above, Cathy has a bizarre obsession with cats and has the ability to communicate with them. Her obsession goes to the point that she decorates almost the entire interior of her house with cat-themed paraphernalia. She has a habit of dressing up in cat-themed clothes in the Gothic Lolita style and sometimes exhibits cat-like behavior; i.e. curling her hands to simulate cat paws, finishing her sentences with the word ニャーnya and licking her lips. She also has a habit of saying the word "Cat" (かとkato) when talking.
Cathy has a habit of saying "cat" (キャット, Kyatto) or "meow" (にゃ, Nya) occasionally. She also mixes them with words sometimes, like with her version of "Kattobingu", which is "Catbingu" (キャットビング, Kyattobingu).
Cathy stalked Yuma, appearing in the background of several scenes, hiding, such as appearing alongside other students after Yuma attempted to swim the length of the pool in gym class (she and Tori were the only students not laughing). She was also behind Yuma before he started his first Duel against Shark.
She then later appeared when she snuck into Yuma's bedroom and swapped his clothing (multiple times) with something that would anger Tori, which worked excellently as she wanted Tori and Yuma to fall out. Then when Tori offered to take Yuma shopping for more clothes, Cathy set a trap for Tori to keep her from meeting up with Yuma on time; by doing this she was able to take one of Tori's ribbons to attract Yuma to save her. She then Dueled Yuma, gaining an early advantage with the capabilities of her "Cat" Deck. Yuma helped her get the confidence to introduce herself to her secret crush, with Yuma being completely oblivious to the fact that he himself was the crush. She would lose the Duel in the end, being the first opponent Yuma defeated without the assistance of Astral or his "Numbers". She then approached Yuma the next day at school, and said "hello" before running off while blushing. Yuma didn't tell Tori that Cathy was the one who had the cats go to her.
Later, she overheard Yuma's conversation with Astral about Kite. Then she decided to join the Super Secret Number Card Investigation Club hoping that if she understood more about them Yuma would notice her more. When they were captured by Fortuno, she used her cat-like skills to escape and warn Yuma only to be possessed by Jin, returning to normal after he told Yuma he had his friends and wanted his "Numbers". She brought Yuma to Jin's mansion and watched their Duel. She jumped up to Kite's statue and attacked it thinking it was the real Kite until its head came off exposing it as a statue and how Fortuno intimidated Yuma and Astral.
She later accompanied Yuma to Kite's labratory, where she along with Caswell managed to destroy Orbital 6. Later when the building was beginning to explode, she was reluctant to leave as she along with Tori didn't want to leave Yuma and was seen mourning his death after the building had collapsed but was overjoyed to see he was alive when he emerged from the rubble.
World Duel Carnival
Cathy attended the World Duel Carnival opening ceremonies with the rest of her friends and was surprised at Yuma not receiving a Heart Piece. When the tournament began, she witnessed and was surprised at Flip and Bronk Stone running off out of excitement in order to find Duels just before she witnessed Striker kicking a ball into Yuma's face and challenge him to a Duel.
During Yuma's Duel with Striker, due to the effect of his "Stadium of Dreams" Field Spell Card, Cathy along with Caswell were transformed into commentators for the Duel. During the Duel, they commented on the moves that each Duelist did, and were both overjoyed when Yuma won.
During the second day of the World Duel Carnival, Cathy approached Yuma after his Duel with Nistro and Dextra, revealing that she had only won one more Heart Piece. Soon after, a dog snatched Yuma's Heart Piece and ran off, causing Cathy to send her cat army to look for the whereabouts of the dogs. After Cathy found out, she went to the location and was threatened by a pack of dogs, to which her cat army soon appeared to defend her. The leader of the pack of dogs, Pip appeared before Cathy and challenged her to a Duel, which shocked her and the rest of her friends as the dog could not only talk, but Duel. As the Duel progressed, Pip managed to get an overwhelming advantage, but a direct attack from Cathy's "Cat Girl Magician" managed to damage a device on the back of the dog, which revealed that the rest person Dueling was a little girl, who was the real Pip. She revealed to Cathy that she was too nervous to Duel face-to-face therefore used her dog as her front. After Cathy and her friends spoke to Pip, she managed to muster up enough confidence to carry on the Duel on her own, even managing to win. After the Duel, Pip gave Yuma the stolen Heart Piece back, but was rewarded by Cathy with her own Heart Pieces.
On the morning of the third day of the World Duel Carnival, Cathy along with the rest of Yuma's friends appeared before him in order to cheer him on in obtaining his last Heart Piece. They all then decided to go and look for a weak opponent for Yuma. Cathy decided to ask her cats to find one, quipping that its a shame that she Tori can't do the same with birds. Cathy then ran with the rest of her friends to where Flip told them to meet him, where they all watched Nelson Andrews Duel Nistro. After the Duel, Nelson said that Dueling causes Yuma to make people happy, including Cathy.
When Yuma decided to Duel Trey, Cathy along with his other friends decided to cheer him on. When Trey shackled Astral to a monolith, Cathy was shocked to see what Trey was doing. After Trey took Yuma's "kattobingu" spirit, Cathy attempted to cheer Yuma on to continue and when he almost fell off of the road, Cathy assisted in pulling him up, but was thrown to the side and trapped within a barrier by Trey. When "Number 6: Chronomaly Atlandis" along with "Final Prophecy" began to drag the group into the Barian World, Cathy was scared, but was overjoyed when Yuma managed to revive Astral and combine to defeat Trey.
After Yuma qualified for the finals, he brought Cathy and the rest of his friends with him to the party that Mr. Heartland threw for the finalists. She sarcastically complemented Tori's outfit, saying that people need nice clothes to look good, just as little birds need feathers. Tori retorted that Cathy's "cat demon cosplay" outfit looked good too. Yuma forgot his invitation, so Flip led them underneath the red carpet to get through the front door. Chased by bouncers, they were let in by Nistro, who vouched for Yuma being a finalist. The next day, she and the rest of Yuma's friends woke him up, as he had been sleeping at Heartland's gates to avoid missing the finals. They proceeded to the Duel Coaster Stadium. Yuma realized he had forgotten his Heart Pieces. Kari runs them from Yuma's house on her motorcycle and Yuma's friends station themselves at point around the path inside, throwing the Pieces to each other. Cathy caught the Pieces from Caswell and jumped across some building to throw them to Flip. She then watched the tournament continue from the stands. After Fakers defeat, she alongside the rest of her friends watched the Duel between Yuma and Kite.
Yu-Gi-Oh! ZEXAL II
Cathy was defeated in an off-screen Duel by Fender, alongside Flip, Caswell and Bronk.
Later, she and Tori get into an argument, but started to make up during the Friendship Games. However, Girag brainwashed them, instructing them to Duel Yuma for his "Numbers". Both were returned to normal after being defeated by Yuma and Girag.