Rebecca is, in the original Japanese version, the American Duel Monsters champion, formerly held by Bandit Keith. In the English anime, she is the Intercontinental Champion. Rebecca is also the granddaughter of Arthur Hawkins. She is twelve years old in the original Japanese anime. In the English anime, she is eight.
Rebecca is the granddaughter of Arthur Hawkins, an old friend of Yugi Muto's grandfather, Solomon Muto. Rebecca encountered Yugi as he returns from Duelist Kingdom. She accused Solomon of stealing her grandfather's prized "Blue-Eyes White Dragon" and demanded he Duel her for it, when asked about how she knew that Solomon "stole" the card, she replies that Keith Howard told her, although it can be presumed that Keith merely lied to her out of annoyance, indicating that she tried forcing the information out of him. As he was recently discharged from the hospital, Solomon cannot Duel, so Yugi Dueled Rebecca in his place.
While they Dueled, Solomon recounted how he met Arthur, an archaeologist who believed that the ancient Egyptians played an ancient form of Duel Monsters. Arthur's colleagues laughed at his strange ideas, and he set out on an expedition with Solomon to find proof. They were trapped when a tomb caved in, and as there were only enough supplies for one person to live, they Dueled for them. Now, Yugi and Rebecca are fighting, card for card, the very same Duel, and Solomon claims he knows how it will end.
Rebecca discarded various monsters to her Graveyard to power up her "Shadow Ghoul" monster, and Yugi conceded defeat. Rebecca demanded the card, but Solomon reveals it was destroyed. An angry Rebecca yelled at Solomon (unaware that it was really Seto Kaiba that destroyed it) until Arthur arrived, telling her to behave. He showed Rebecca the card Yugi had drawn before he forfeited. That card was "Soul Release", which would've allowed Yugi to remove five monsters from her Graveyard, which would've weakened the "Shadow Ghoul" just enough for Yugi's "Dark Magician" to destroy it. Yugi admitted that he surrendered on purpose, just as his grandfather did to let Arthur take the last of the water that they had. When they were rescued, Arthur was so grateful that he gave his "Blue-Eyes" card to Solomon. After learning about the story, Rebecca quickly apologized for being mean to Yugi and not listening to his side of the story. Yugi gave Rebecca his "The Ties of Friendship" as a reminder of this lesson, which she kept ever since.
She and her grandfather returned in the Waking the Dragons arc to help Yugi fight Dartz. Here Rebecca appears noticeably older-looking and wearing glasses (to the point that everyone barely recognizes her) and is also in college, much to the shock of Yugi and the gang.
She helped by researching Dartz's Three Swordsmen and hacking into KaibaCorp's computer system to track others via their Duel Disks. She also seemed to be slaving under the delusion that Yugi was her boyfriend (her "darling" in the Japanese version, a reference to Urusei Yatsura), something which made Téa Gardner jealous. This didn't seem to be a pretend crush as she was devastated when Yugi's soul was taken and tried to defeat Valon in vengeance, showing she had true feelings for Yugi. However, she and Duke were defeated by Valon easily.
After Dartz was defeated, the gang stayed with Rebecca and her grandfather for a while. Rebecca then took part in the KC Grand Championship, where she defeats Chinese champion Vivian Wong and Abe the Monkey Man. She lost to Leon von Schroeder in the semi-finals and spent the rest of the tournament cheering from the sidelines. She is absent after the tournament ended, telling Yugi that she will Duel him again one day, and telling Téa (with a coy look) that she will miss her.
Her appearance in this arc is different from her appearance in Waking the Dragons. She still keeps the short skirt, but wears it to cover her legs. She also wears a light blue top over a grey T-shirt and reverted back to having two pigtails.
In the Japanese version of the final episode, Rebecca made her final appearance by hugging Yugi at the airport while Tea glares at the scene. This scene was placed at the end of the Grand Championship arc in the English dub.