We now need a prequel with Saya, what made her zoom in on the dark gloomy MC, and a Noguchi chapter so we can find out if the quiet glasses girl is actually kinkier than Reina and Saya combined.
Sequel idea: 18 years later the young boy is now a newbie gym teacher the unborn is a girl and is a senior in high school. Being his father's son a bunch of half sibling steaminess ensues. I say at least three chapters before they find out they have the same dad and by that time they're too into each other to break it off.