After a forgetful moment leads high-school student Tamao Hiroi to use the back entrance to his home, he is shocked to discover a surprise occupant in his bed. To his amazement, the person turns out to be Ran Homura, a younger student renowned for her softball prowess and captivating beauty. Witnessing an intimate moment, Hiroi finds himself drawn into a peculiar 'master/slave' dynamic after a revealing encounter through a glass door.