While I agree that Leo is fucking annoying and I dislike him as well, he's used well to show the maturity of the MC. Even though, I wish that in the future that genre starts to be tuned down a bit, and maybe Melana helps on that.
Don't get me wrong, I like this game mostly because of it's writting, and I get the reason of Leo having his appearances. Even though, while I understand the reasoning to use Leo in writting, mainly for comic relief, after some time it gets tiresome. If Melana has that goal, then I wish that the MC helps him to have his redemption arc or if not, simply dump him at some point.
I accepted Leo at first because I understood it's objetive in the game, but since the "genre" is the same on each update over and over it starts to be a bit tiresome to even tolerate his lines in game. It even increases even more the feel that the MC is "growing way too fast" (than it should) compared to his age and his classmates. Hopefully Melana changes that a bit, even if he still remains somewhat innocent and oblivious.
While she's annoying af, I actually don't dislike her model...
I know some will call me crazy, but to this day I still feel that Viktoria and her mom give all the vibes to be a perfect cousin and aunt. Sure this won't happen, specially at this point of the story, but they clearly give that feel at some point, specially the mom.