I feel like people are being pretty harsh on Chi, considering how little we actually know about her. Inuyama also fell pretty flat early on—back when all we knew was that he was Seto's friend and a pervert. That's roughly the level of development Chi has received so far.
One thing I do agree with is that this should mark the end of the setup phase. The author should now push the relationship forward, whichever direction it's going—be it love, friendship, or something else.
With the other two couples more or less wrapped up (the author could give each of them 2–3 chapters of epilogue—Seto and Anjou focusing on their relationship while navigating daily life, and Inuyama and Toyoda continuing to challenge and inspire each other artistically, with their romance developing more organically alongside their shared goals), I'm still most interested in seeing where this relationship is headed.