@Random_Passer-by
From a certain point I can see why you would say that about the romance(although there was clear romantic progression on Yuusuke's part, and even some romantic flags, although more subtle, on onee-san's part too) but I have to completely disagree on your second point, there was clear character development for Yuusuke.
Well, the characters in this series in general were more realistic/grounded and were more like actual characters instead of your usual romcom were the characters are basically tropes. Anyway, guess different strokes to different folks, not everyone will have the same view about a series.