What if Haruna is YuukoRena daughter from the future and falls in love with Yuuko-sama from 2015? Okay, that's a weird theory, I know xD
It makes me curious, this one thing... If it is fated for Rena-sama to die, and Yuuko-sama saves her, there's always a price...so either Rena-sama dies in another way or some other trahedy happens....
I'll be waiting for your next update ^~^