With summer finally here, the Misato household is due for a thorough cleaning. Unfortunately, ex-battle android Mahoro's rigorous scouring finds a dirty book that triggers a battle of the sexes. Enlisting the help of frail Minawa, shy Miyuki and the harlot Miss Shikijo, the females make it their mission to destroy the naughty pictures. Suguru, Kiyomi and Toshiya realize the trouble their dirty secrets are in, and must do whatever it takes to protect their treasure from the girls. Will the boys be able to keep their voluptuous material hidden, or will Mahoro assert her authority and convince them that "dirty thoughts are bad"?