[Kinnkuruhositinnkuru (Chio)] Futanari Shimai no Seijijou [mysterymeat3]

The futanari sisters of one very demanding family keep their men exactly where they want them—under a bare heel, at the end of a string, or begging for another round. Caught embezzler Koutarou pays his debt beneath his blackmailer's foot, while would-be predator Kyousuke ends up the one captured, entranced and dutifully 'reformed' by honor student Shizu. Even youngest sister Rokka displays the family talent, working poor Satoshi over with toys until he's a drooling, trembling wreck who can't get enough.