ハルキの最大の敵は理性。

The girl he's in love with is coming over to his place, alone. Tagokoro Haruki decides on Saturday to prepare for this situation.

Haruki is a virgin, as his raging boner in the morning can prove, and his step-sister — Tagokoro Anne — plots to fool around with his fluttering heart. This leads to him skipping his Saturday shift...

During lunch time, his remarried step-mother — Tagokoro Madoka — plans on seducing him as a way to satisfy the itching inside her. She decides on doing that on that Saturday, when her husband is out of the house.