Akari - As the oldest sister, Akari takes the role of the mom figure in their house, though that doesn't mean that they don't act like sisters, they are constantly fighting over everything but they always make up because at the end of the day they love each other.
Momo - She is the youngest sister of the three and is usually seen with Hina or Akari, especially when they go to see Rei.
Rei - She really appreciates him and just as Akari, she is always there to make sure he is ok and thinking about him after he's disappeared for a while. When she makes a bento box she always makes another one for him or has him there to make sure the food tastes good.
Kyouko - When she first meets her in when she's in the middle of an argument with Rei and her presence makes her feel uneasy, she really cares for Rei, and when she meets him again expresses that she needed to know who she was because she could feel how Kyouko was the one causing the argument and that Rei was on the receiving end.