I did not get ANY romance vibes from their dynamic at all until these last 2 chapters. I thought it was father-daughter or annoying sibling dynamic considering how immature Ruri's personality and appearance are. If she was a human I would peg her at 14 ignoring the fact that she drinks alcohol...
I somehow didn't notice the inner hair coloring at all until the author mentioned it lol. The shade of pink and blue on the cover is a nice contrast, though more blue would make it feel more balanced