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.
Fridge Brilliance: Initially the premise seems downright insane, but when one stops to think about it, the true genius of the concept becomes clear enough to make one wonder why no one thought of it sooner.
What an Idiot — Even taking into account his total lack of experience and some sexual Values Dissonance in Japanese society, Makoto is very, very bad about thinking of Yura's pleasure during sex. Even after detailed lectures from both his brother and sister-in-law about the importance of foreplay and how to please a woman, he's still awful at it. In his defense, this is probably Truth in Television for too many relationships. (And a main point of the manga.)
Tear Jerker: The ending of the first short story. Okay, someone get a box of tissues.