You made her your attendant

In the end, you have Midori move into your house where she becomes your attendant. Just like a maid, she would help you to prepare for your day to day life, from preparing your uniform to keeping your room clean.

Of course, she helps relieve your desire as well, keeping you satiated so that you can concentrate on your studies.

Almost each day the two of you partake in the primal act of procreation, deliberately wanting to bring forth a new life that carries both sides of you. Not just once other people stumble into you and Midori in the act as you take her wherever you like. Walking together with her at a garden inspired you to take her there and then, as you feel the need to sire your seeds into her own fertile garden, with the hope that your child would grow from it. As you came down from emptying yourself inside her, you don't really care that your sister and another attendant saw the two of you being half-naked and in the act of copulating.

Another time, she was in the kitchen preparing your food when you get behind her, loosen her yukata just enough to stick your dick inside her pussy. A quick act and you empty yourself inside her. You thank her and return to your room, relieved and ready to do your homework.

As the two of you wanted, one of your seeds took hold and your child began growing in Midori's womb. One day, while you're lying on her lap, she tells you the news.