Seriously, why does it even matter who Rena is? Other than to fulfill the bullshit "first girl wins" cliché, I can think of no other reason why it would matter at all. Maybe I've forgotten some stupid plot point over the course of 85 chapters. The whole "quintuplets swapping identities" thing doesn't really add anything either. It's just bullshit to needlessly obfuscate things in an attempt to draw everything out longer.