I hate when Japanese writers don't know how to progress a relationship, so they just add a rival character
It didn't need another character, but sure, add an annoying rival that would live only for a couple of chapters and wouldn't actually do anything except be annoying
This was really boring and disappointing
Sorry replying so late, but I think this one character just only serve as a stepping stone for the progress, like the author didn't know what to do to make her (yuzu) notice her feeling. Her character is kind of a waterflow that would just go with the story as I notice this far,
not much like a heroine, but more like a goal for the other party.
So, how to make her not flow with the story and advance the story progression? Make her experience a same thing as what Minami had been through, but maybe do it differently, and so that is her character's purpose.
But really, I hate it too when japanese writers just dump a disposable character like that and let it speedrun story progression like a man running from a fused bomb on the ground freshly dropped from an aircraft at low altitude.