``Practical sex education,'' which began as part of a measure to combat the declining birthrate, is sex education in which teachers use their own bodies to provide ``direct instruction.'' - A married female teacher with a husband and two children decides to teach for the sake of her students, even though she struggles with embarrassment and guilt toward her family. - Direct sexual guidance from male teachers to female students, as well as cases of male students running out of control with their sexual desires as they develop feelings for the female teacher who has returned to work after giving birth...! - ?