Hiroki doesn't know that Megumi is acting the way that she feels someone who has been dating for a while and has gotten serious would act with her boyfriend, buying clothes for each other, showing off what they bought by wearing it in front of the partner, and even changing clothes from the birthday suit, out in front of each other, maybe even wrestling in the bed together, that's what being serious is all about, but Hiroki grew up without a mother from an early age, so he didn't have the influence of an adult woman in his life, except through his friends if he played at their houses, his sister is a little different, she had their dad at home, plus girls have a tendency to act together, more than boys do, to share what they learn and they like to pretend that they are sophisticated like the women they see in the movies and plays they watch, as well as communicating about their experiences in dating and sex, girls love to talk about the opposite sex and sex more than boys, if you ever get around a girls only party when they think their alone or have forgotten about the server or anyone else around them it can get outrages. When Hiroki goes on dates with Akira or Megumi, if they are acting the same way he might start to understand, but as dense as he's been I doubt it, thanks, the story is making me think, it's interesting and very enjoyable.