[Fujisawa Tatsurou] Lust! Sisters Raw Underwear (Hitozuma Hamegurui 7)

When his older sister Aki abruptly moves back home after leaving her husband, a lonely virgin finds himself at the mercy of a teasing, full-figured woman who already knows exactly how to torment him—and who once caught him with her underwear. Emboldened by his confession that she was his first love, she declares she'll 'make a proper man' out of him, and their secretive nights of raw, frantic sibling debauchery escalate until their parents catch wind of the noise. The frantic finale promises more trouble ahead, with mom hinting she might want in on the family fun.