The protagonist's remarriage leaves him with two daughters.
The girls hesitantly decide to live in harmony with their new father, but their mother has chosen the wrong partner.
Although he's usually a serious and gentle father, deep down inside, he harbors a powerful desire to rape his beloved daughters.
He wants to pour every last drop of his boiling hot semen into the most precious parts of their supple bodies!!
His dark desire grows stronger with each passing day.
Using the "love drug" he developed to make his beloved daughters slaves to pleasure before they become another man's possession!

[Modified from DLSite, archived]