Doraemon (1979)

The Room Guard Set (6x38)

Air date: Sep 28, 1984

To keep Nobita from getting scolded by his mother, Doraemon uses a Room Guard Set that prevents her from entering his room without the correct password. However, when Nobita changes the password to a harder one, he forgets it—leading to a shocking outcome! This episode was later remade as Entry to Nobita's Room is Forbidden in the 2005 series.