Shirayuki sensei to kodomo tachi (1950)

A grade school in Tokyo, where students curse and gamble, has a pond on-premises with one particular teacher who is in charge and takes care of it. The pond holds a number of carp, but someone is snatching them. Amidst the student, one lives with his mother in poverty. The mother works at a factory whose owner is a member of the parent-teacher association and asks her son to help her employer's son to help with homework. Her son is not happy spending time doing this. Finally one day the teacher finds out who is stealing the carp when the poor boy finds out and reports it. It is a child who is not attending the school.