Class 3-Z of Gintama High School—led by teacher Ginpachi Sakata—is known for its eccentric students who have a difficult time with their studies. Moreover, Ginpachi and his students often run into trouble with the school's demanding principal and the class' feared delinquents, who have returned from a suspension.

Despite all the chaos and Ginpachi's idle attitude toward teaching, his students still dearly respect him. Although constantly derailed from their studies, Ginpachi and his zany class always find a way to keep their school days entertaining.