There is a known series: (Kissed with girlfriend's little sister) or "Kanojo no Imouto wa xxx" tropes, but not exactly your string.
: The primary "antagonist" or love interest is the "Nikushokukei Gal" (a "carnivorous" or assertive trend-conscious girl) who actively pursues the protagonist, creating a central conflict rooted in forbidden romance and sibling rivalry. doujindesutvkanojonoimoutowanikushokuk exclusive
If you’ve been deep-diving into recent doujinshi releases or trawling through file-sharing forums, you’ve likely stumbled across a long, fragmented search string that looks something like: There is a known series: (Kissed with girlfriend's
: A classic exploring complex sibling relationships within otaku culture. you’ve likely stumbled across a long
