I completely disagree. Having Hinatazaka appear on stage would just make their independence feel less important. I doubt any Hinata fan wants that (especially not those Hinata fans who dislike Keyaki) and I honestly doubt the Hinatazaka members want that either. Like someone else also mentioned, Hinatazaka has a song about wishing to perform at Tokyo Dome. They'll get there on their own. No Keyaki fans denies that Hiragana Keyaki helped Keyaki get to where they are, but Hiragana Keyaki is no longer a thing. There's not point of them participating in such an important event like the first Tokyo Dome concert. As for Soredemo Aruiteru and Happy Aura being as Keyaki as Techi's solos I don't really get how you'd come to that conclusion. Those are Hiragana Keyaki songs period.