Hattori saves Kenichi from his teacher (The Angry Teacher) (おのれ憎っくき先生の巻) is episode 2 of the Ninja Hattori-kun 1981 anime.
Hattori confronts Kenichi's teacher in this episode.
Kenichi complains loudly about the homework that he has been given. Hattori says it is very good to study hard, but decides to give his teacher a hard time upon hearing about his tyranny. Just as Kenichi is leaving for school, a police officer comes and inquires about a ninja. The Mitsubas pretend that Hattori is not around, and the policeman leaves. Hattori then reveals that he nicked his gun, and goes to give it back. However, when Kenichi's teacher comes, he gives the gun to Kenichi, who reveals that the policeman left it behind. The policeman comes back, and the teacher gives the policeman his gun after scolding him for his carelessness. On the way to school, Hattori follows Kenichi and the teacher. When the teacher asks why Kenichi is ranting at somebody to stop following him, Hattori appears, and the teacher runs away in fright.
Arriving at school, Kenichi and the shaken teacher sit down. A tall girl with long black hair named Yumeko Kawai asks the teacher, whose name is Koike, why he is so scared. Mr. Koike then pulls himself together, and then begins beating the people who have not done their work. As he comes closer to Kenichi, Hattori sets a stinkbomb off and traps Mr Koike to the branch of a tree. Kenichi scolds Hattori for doing that, and Hattori apprehends him by attacking him with some ninja stars.