Ayane's daughter and son-in-law have bought their own home, and with the end of their time living together approaching, Ayane feels lonely. Then a chance accident reveals just how huge her son-in-law Makoto's cock is. Sexually frustrated and unable to contain her lust, she greedily latches onto it. Makoto cannot resist her seductive display and becomes addicted to his mother-in-law secretly getting him off at home. Their affair was supposed to end when he moved out, but before long he could no longer go without Ayane's body...