I really, really wish the premise of the manga was just literally the title. If the childhood friend never existed, nanao would not be divisive and there are about a thousand other hooks the author could have used instead of the one that belies an end goal instead of just setting up a plot. A much better way of going about this, IMO, would be to have resolved the premise first and then do nanao second so that people who don't care can stop reading once the part they were invested in is done, and those who like her can just keep reading. This whole arc was honestly just the worst possible way it could have been done and it has made me very bored.
But well, too late to change any of that now.