I guess the atmosphere is not romantic in the typical sense but I can see the sexual tension. Yotogi shatters Shiho's first impression of her as an innocent kindred spirit by revealing herself to be something Shiho fears and forces Shiho to admit her true desires. I would even say this opener could have worked as a one-shot. That and the other girls on the thumbnail makes me concerned that their relationship will see little development in the rest of the series, and random cosplay shenanigans involving the other girls will get most of the focus.
Well, I could be wrong. Maybe Yotogi will keep turning up the heat on Shiho. Kissing in front of a crowd while in cosplay, bolder outfits, private photoshoots...