This is one of the handful stories where ill actually feel bad for the loosing heroine Otobe.ultimately I feel like everyone but Kusunoki is going to lose, assuming the contest is romance and Keisuke is the prize. That's entirely based on the formulaic way these stories are often written, and with what just transpired with Otobe this chapter, it's already started trending more and more into very well-trod territory with Losing Heroines As FMC Plot Devices.
It sucks, because I like Otobe more, and I think Hebikawa is the most interesting character of the cast thus far with the greatest potential for velocity in her character arc; but banking on authors taking risks and subverting the expectations of their reader base is a fool's errand, in my experience.
Maybe this author will buck that trend and go a different direction, but I will not be holding my breath.
As far as Backstory goes, I suspect you will not have to wait long.
I want them both to win but they cant, which sucks. If otobe ends up winning Id be satisfied, unlike other stories where the loosing girl is purely a plot device.