Worried about her daughter who has started living with her boyfriend, Chisato suddenly comes over. However, even though Chisato is there, the two of them make no attempt to hide their lovey-dovey relationship, which makes her heart race. At night, as they sleep side-by-side, her body begins to ache as she hears faint moans from next door. Even though she knows she shouldn't, every time she hears the sound of clothes rustling, Chisato's excitement rises. Finally unable to hold back any longer, Chisato takes the opportunity while the two are asleep to straddle her daughter's boyfriend and engage in co-sleeping sex...