Jessica Case is a young teenage multi-millionaire that goes to Domino High School or to put it in clearer terms, her family owns half of the school. She is what everyone would call evil, greedy, and selfish, but mostly evil. She isn't as rich as Seto Kaiba but what she does with her money is dig up information on others and uses that dirt on everyone at Domino High and uses what she finds out as blackmail to get what she wants out of people. Which leads into getting her little posse to do her dirty work. She has her own little sorority group at the school and almost every girl has joined it and regretted it.

Now, switching gears, she’s also the last heir to the Case family fortune. She has to marry as soon as she graduates. But when she finds out that her fianceé, Tomiichi Takaishi, went to America and fell in love with another woman, Jessica was furious. Tomiichi wanted to break off the engagement but Jessica wouldn'’t let him. To show him she meant business, she started targeting the girl that he'd met in America, and her friends. But in the end, the engagement was broken off and Jessica was accused for hiring a sniper to shoot and kill one of Haruka's friends but it was never proven.