The plot of Happy Lesson is based on five teachers who end up living with a troubled and indifferent orphan and their unusual plan to become mother figures in an effort to make him a productive student. To achieve their plan, they employ various methods, such as science experiments, spiritual cleansing, physical training, and hijinks. Despite superficially resembling a harem anime, the show is unusual because it has very little romantic tension and a male lead who is closer to the "good-hearted delinquent" personality rather than a measly nerd.