Since you can't really show sex scenes on public broadcasting TV, sex between lovers is either implied or shown for a brief moment as they lay down in bed. The challenge is to actually find a romance-centric hentai from a trillion other hentai shows that focus more on the rape and tentacles. As we have mentioned before in our articles covering hentai titles, the hentai genre is very flexible and not exclusive to the aforementioned rape and tentacles. What are the criteria? The story must focus on the couples that started out as friends and then became lovers.