I like the general atmosphere, and... Art direction, I guess. It feels somewhat art-housy, especially those little sequences that do not server any plot, but work only for the atmosphere, making it feel a bit more... Natural, perhaps? Especially that sequence at the end of the episode, where Ayase was figuring out the lights. This can definitely work as a movie, without anything changing even.
For a 12 (or more?) episodes, though that would be a difficult sell, so they need to change something in next episode, or at least give hints on something starting to change. Because otherwise it will just be boring. On other other hand the overall premise is somewhat questionable to being with. I mean, yes, media telling that love blooms between step-siblings right away is exaggerating things, to put it mildly, but it does not mean they can't become friends. Do not think it is really common to kind of form a pact to stay away from each other.
But again, this may be part of the characters: they could be both introverted, or just tired or whatever else, and they just want to be able to peacefully co-exist. Which is totally normal in real-life, but may not be enough for the show. Let's see what will happen in 2nd episode.
