I just finished watching Princess Princess today, and was going to read Princess Princess Plus. I couldn't find it, and then I heard about this manga and decided to check it out. I didn't realize it was about Sakamoto and his family, so that was a great twist. Now that I know this, I'm going to read Kakumei no Hi for the same reason. This should be a good read, though I still wish I could find Princess Princess Plus somewhere online.
Great first chapter. I laughed so hard after the little sister said she was flashed and the family went silent. That was hilarious. Poor kid.
I look forward to learning even more about Sakamoto's family. :)
EDIT: Take it back. Not going to read Kakumei no Hi. I read one of the reviews, and then I read part way through chapter one. It has pretty offensive views on gender identity and sexual orientation.