In the end, it can’t be said for sure whether or not the woman on the train was indeed Natsumi Takamori or not.
“You three are causing problems for the subway service, so get off the train already!
The station attendants saw you at Otemachi, and you’re already causing problems for them.
But if she, in fact, isn’t a professional voice actress, she’s definitely got the enunciation, projection, and emotion to make it in the anime industry.