Miyamoto would be the type to be excited for a love rival, huh?
Though since he's a defeatist that's convinced himself he's too far out of either of their leagues, it really comes to who can woman up first and confess, huh?
Edit: wait is that "the penpen clock doesn't work even with new batteries" some incredibly obvious foreshadowing or am I overthinking it
Edit 2: may as well just use spoiler tags. I think it's more or less foreshadowing a Koi-chan loss, at least as she is. The penpen clock doesn't work anymore, even with new batteries. It's stuck in the past. Their only real bond is with penpen, as Uehara shares the mangaka dream with Miyamoto as the two of them navigate having to become mangaka in the first place, as well as the strong support they've shown eachother that makes them both stronger as both mangaka and people, versus merely helping Koi-chan, who already has achieved that dream. Miyamoto also drags him around to all sorts of new experiences and places he'd never have gone himself, that I feel Koi-chan wouldn't take him to since they're both so introverted. Unless she can strongly bond with him in a similar way to his bond with Miyamoto, just penpen won't be enough, and the past is the past. If Koi-chan doesn't bow out, it feels like a race to see if she can charm him the same way before Miyamoto can overcome her preconceived notions of both of their ideal partners. Though they both probably have an uphill battle since his insecurities on how he's perceived when out and about with either of them are on full display again... ultimately, though, I think it's still Miyamoto's win, given how much he's improved himself with her help and encouragement. That's how I'm interpreting it, at least.