These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
There seems to be some sort of chemistry going on between Chimo and Riho during their first encounter. Chimo is quick to decide to let Riho stay at her place, in any case, and there are hints that the two are indeed together later on.
Norie sometimes likes to tease Kaoru rather suggestively.
Moe: In-universe, Kou to Norie. To the audience, Fuu.
Purity Sue: So many characters are still mourning the loss of Kazuma Sawatari years after his death. Even people who have never met him go out of their way to help his daughter learn more about him or put their normal behavior on hold so as not to interfere with her quest. He must've been a real saint to have that much of an influence on that many people. It gets a little too much to suspend disbelief at times.