Ai Kaga is a student in Class 2-H in the anime series 'Sayonara Zetsubou Sensei.' She is characterized by her extreme apologetic nature, constantly believing that everything is her fault and apologizing profusely for things beyond her control. Her exaggerated sense of guilt makes her a source of both comedy and sympathy within the series. Ai interacts frequently with Nozomu Itoshiki, the protagonist, and her unique personality contributes to the satirical and absurd humor that defines the show.