Ah, that character in the right bubble is Amemiya-san! With CITY finished, her manga is now the newest serialized work by Arawi Keiichi, in Monthly Shounen Sunday, paired with some animated work on his YouTube channel and some art on his Twitter.
For now, I'll just tag her as Amemiya-san and leave original as her copytag. If we ever find out her full name, what is currently her chartag can be turned into her copytag instead.