@Ghostdevil I wouldn't say so. It was just a boring day. Kids, like the twins, need a hundred things to keep them entertained for a longer period of time. Haruki is merely one of them. Yayoi needs him for homework help, but that only makes him a helper, not a center of anything. With Mutsuki, he's actually the one she doesn't mind when she wants to relax, or, in other words, can ignore. So, she can be lazy in his company, but not the younger siblings' company. However, don't be mistaken, she doesn't need him for that. She's sleeping in his bed just fine when he's not present, but won't bother getting up when he appears. Any of the other kids, and she's immediately up and proper. This also mean the younger kids are far more effective in getting Mutsuki back to work. They merely need to be there.