Maina is a polite, pure schoolgirl with excellent grades. Both at home and school, she is known as a model student, highly regarded by her neighbors and teachers. However, she secretly harbors a naughty desire for exhibitionism. One day, plumbers hired by Maina's parents visit her home for water pipe repairs. Seeing the men, Maina acts on a shameless impulse. Unbelievably, she exposes her genitals right behind them while they work. Noticing her actions, they pin down Maina's innocent body...