I predict this is a false flag. Ushio will help move the story along by introducing the element of competition but isn't interested in Seo as she already has an otaku of her own.
I don't I believe I'm saying this. She has short hair and is almost a tomboyish gal (both things I'd sell my soul for to have in my gf) But I don't feel the goofy fluffy feeling seeing her and Otaku-kun's interactions.
This new girl is not appealing to start off. Honestly, even considering classmates, family members, and other limited side chars, this new gal is the first character in this story that just comes off like an arsehole, and I can't say i like it, but maybe she'll improve.