Seeing Noah is completely fine Sia made a surprised sound since she wasn't expecting this. It was the same for the monster; they also hadn't expected something like this to happen.
"Senior sister Sia, senior city Lord you guys can go back, there is nothing to worry about me, I'll catch up to you guys and we will hold a great first together after this end" hearing Noah's voice even after witnessing Noah's power, Sia still decided not to leave. But City Lord suggest her " this is the best choice after all we will only get into his ways,"
Hearing this Sia decided to go back, but when she was thinking the monster would attack them, surprisingly they didn't even look toward them and kept looking toward Noah as if trying to find out what this being made of.