Sayonara Zetsubou Sensei - Season 1 Episode 12 What an Incredible Bother!

The first part of this episode introduces Ai Kaga, a girl who always takes blame for everything, even though it is not her fault. Nozomu takes the class to a "guilt scramble" to explain that history has led to the "guilt complex" such as Kaga's becoming the Japanese mentality. After being overcome with guilt himself, Nozomu and Kaga travel the world to try to stop burdening others. The second part introduces another girl, Mayo Mitama. Her evil-looking eyes have led to her being misunderstood - that is, she actually is evil, but people try not to prejudge her and assume she is actually good. She commits several cruel acts that Nozomu bears witness to and is blamed for, being the only other nearby party. He becomes so concerned with not prejudging that he doesn't blame her when she hits Majiru over the head with an aluminum bat or when she drops a brick onto Nozomu's head.