Tetsuro, the father-in-law who lives with his son, has recently become increasingly senile, and often causes trouble for his son's wife, Kotone. However, Tetsuro takes advantage of this and attacks Kotone while she is bathing, pretending to mistake her for his late wife, Setsuko. Having gotten a taste for it, Tetsuro waits when his son is not around and licks and devours Kotone's pussy in the same way, finally penetrating his lustful flesh into her vagina. Unable to tell her husband about the lewd acts she had done with Tetsuro, she is tormented by her father-in-law's dick and repeatedly orgasms in convulsions...