Feels like what's this manga about is wether F-cup chan is strong enough to bear that MC is popular with some girls and kind to everybody.
if she can't get past that, Blondie get the kill
So now she tries to rely in some sort of curse to be sure she will be tied to MC.
Which is a really shitty situation imo, as i root for the blondie, which seems a more interesting character, i'd hate it if she win as the choice of substitution
Mc needs to wake up : Satsuki >>> F-chan. Then again maybe he still thinks Blondie is kind to him out of guilt.