To solve her erectile dysfunction, the father-in-law, upon seeing his daughter-in-law's body, achieved a full erection again after six years. "This might be the last time I get an erection... Let me penetrate you just once..." Forced into this union, Mako, unable to forget the taste of incestuous penises, indulges in unprotected sex while her husband is away. (Usui Serina DVAJ-707)

The reason my mother-in-law, with whom I live, ran away from home was because of my father-in-law's erectile dysfunction... To comfort her grieving father-in-law, the two of them tried exercises to promote erections, but to no avail, and the father-in-law became despondent. Unable to bear watching, Serina tried a groin massage, and her father-in-law's penis, which had previously been unable to achieve an erection no matter what he did, gradually grew larger and finally achieved a full erection after six years! "This might be the last time I get an erection in my life... Let me experience the joy of being a man one last time!" With a desperate plea to his father-in-law, who begged for penetration, Serina, out of pity, secretly allowed sex without her husband's knowledge...