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.
Yayoi, wanting to educate your little sister about sex is commendable. Attempting to do so via live demonstrations is sick and illegal, and also hilarious.
Kanna's friends and co-workers attempt to convince Motoki that women like it when you force yourself on them. They are all girls by the way. Even better, not only is Kanna in the room, but she does not particularly disagree, which makes you wonder about her... personal preferences.
No matter how open-minded you are about sexuality, there are going to be moments where you ask "Should they be as okay with this as they are?"
The manga so far has all characters in ero scenes with as much clothes on as possible. And while the OVA is perfectly fine with showing boobs, it still censors every last dirty word, even in written form.