OK, this is really weird, but I can't say it's not novel, so...
Might as well let this play out and see what happens.
I'm so sick of manga rehashing each-others' plots, so I can't complain too much when they attempt something new and crazy.
Maybe the next mangaka copying this will execute the concept better...
That said, another angle to the weirdness:
In the first place, don't Ceres and Haruka look way too much like siblings? They're practically twins.
...Well, I'll blame that one on the artist's lacking skill.