Futaba Sakura - A highly capable "hacker girl"
A girl one year younger than Joker.
She has extraordinary computing power and genius-level programming skills, but is not very good at communicating with others. In addition, she was once involved in an incident and stayed at home.
She met Joker and his group by chance and awakened her Persona ability.
If I had a nickel for everytime Joker was trying to leave the Casino palace when a redhead in a outfit similar to his showed up out of nowhere, I'd have 2 nickels.