After a drunken mishap, math teacher Moromizato ends up having a physical relationship with his colleague, school nurse Kashiwagi. However, since then, Kashiwagi's presence in his life has grown stronger with each passing day...!? Your physical defenses may be weak, but your heart is an impenetrable fortress, and he wants to take you down☆ A headstrong, happy love story for all those who are timid when it comes to love!