Bastion Misawa is an extremely smart and fastidious Ra Yellow student. He duels with formulas, meticulously studying his opponent's deck and calculating the perfect strategy to defeat it. He meets Jaden at the entrance exams, but they don't become good friends until a few episodes later, when they're playing baseball. After striking Jaden out, and then hitting the ball out of the stadium (and right into Dr. Crowler's face) he invites Jaden and Syrus back to his dorm room, which has formulas and calculations scribbled all over the walls and ceiling. Jaden and Syrus help Bastion paint over the walls (since he's memorized most of his formlas and is running out of room), and then they have lunch in the Ra Yellow meal hall, where Jaden tells him "Hey, you're alright, Bastion."
Bastion finds it ridiculous that both Syrus and Chumley have "card crushes" on a few of their monsters. He believes love is a waste of time and brain power. That is, until he duels the Amazoness Shadow Rider, Tania. She duels with the intent to marry Bastion, and while he is at first put off by her flirting, he actually falls for her. When she defeats him and then changes her mind about marrying him, he's crushed. Jaden then takes on Tania, and Bastion realizes where his passion always lay; in dueling.
He remains a loyal friend and ally to Jaden throughout the series.