@kronix - That would be a major spoiler. But consider the pieces of the puzzle here: (1) There are those who think that Anzu has little time to live. (2) Anzu wants to be the older sister, and apart from a few scenes in the first volume, there is no real indication that Ginnosuke thinks of her as anything other than an older sister who is part cat. (3) What about Hayase?
All this will be resolved over the next seven chapters, and especially in the last chapter.