Not even a lover, but a son who is inexperienced with sex. Unable to bear it any longer, his mother Rei decided to use her own body to educate him about sex so that he wouldn't acquire incorrect sexual knowledge. Initially, it was just teaching him how to masturbate or breast milk handjobs and such, but what she thought would be a one-time thing turned into sex, reminding Rei of the pleasures of being a woman. Having experienced this pleasure, her son also began to crave his mother's body more, relentlessly thrusting into her with his surplus energy.
