Absolutely not true. But this one definitely isn't off to a good start if she wants any romancing. She wasn't even presented to the readers as a person that existed at all until after another girl had appeared and gotten close to the MC.
for the most part, her presence alone heals me as much as she does the MC.
But yeah.. unless it's Imouto-first, then it's not gonna be the Imouto-at-last :<