Beautiful. A modern day Shakespeare, indeed. I feel like the chances of this already being planned out when the author first mentioned her having a brother are low, and that just makes it all the better. Literally anything could happen in this manga, and honestly looking at the suspiciously Kimura-looking father in the picture at the end, it's not outside the sphere of possibility that it turns out that that literally is Kimura and that he really does time travel to the path to become their father at some point. And it's equally likely that it turns out Kimura's actually their long lost brother, and that's why he looks like their father.