Second up:
There's No Freaking Way I'll Be Your Lover! Unless... (manga) Vol 1
I thought the set up would be rivals going head to head and then one confesses and the other hates the idea, but gradually they fall in love too.
It's similar, but the real plot is loser middle schooler, Renako, decides going to high school is her chance to change and as luck would have it the girl she gets to sit next to, Mai, is a bit of a celebrity and bound to be the popular girl in school and thus she gets to be in the popular group from day 1. After a certain event they have 1 to 1 chat in which each confess to how hard it is keeping up appearances and how they should be real friends only for Mai to later confess! Renako is unsure and just wants to be besties, so in a compromise they devise a contest to see who can persuade the other better...
It's a bit of a contrived set up, especially the event that leads to their 1 on 1 chat and Mai can be a bit annoying with her cocky attitude, and I'm not totally sold she's actually in love and it's not all some prank, but they do have a good odd couple chemistry. There's a couple of side characters who seem cool, one has literally just a few panels so far, but seems a bit like Misuzu from Tomo-chan which is very good thing and both of them have more fans on MAL than the main 2! So hopefully there will more of them in the future. Would say it's not as good as yesterdays, but I have 2 more volumes already so will probably keep going.