Rider
In response to Rider's suspicious question, the girl looked at Rider as if she was a complete idiot, before addressing her with a voice full of sarcasm.
"Uh, isn't it obvious? I've found it in the middle of the street and, having noting better to do, decided to smash it. Then, I thought I might fly around with it, and just by pure coincidence, I happened to meet with someone who knew someone who looked like this armour. I also just happen to have the same voice, but clearly I have nothing to do with this besides the fact I decided to carry it around for no reason. Isn't that right, Rider?" she said, following it up with a smug smile.
Rider gave the girl an annoyed look. Of course it was not a co-incidence that she had come here, carrying Vanguard's armour and using his voice. The question was whether Vanguard had somehow transformed into a woman with his loyalty to Sakura intact, or whether she had somehow stolen his body and was here to trick them. Nothing he had said gave her any indication as to which had occured.
"Of course it's not a co-incidence", she said, an annoyed tone to her voice. "I never said it was. In fact, your voice is the reason I am still talking to you rather than simply getting rid of you as I was ordered. However, last time I heard that voice, it was not coming from the body of a silver-haired girl...", she said, still uncertain whether this girl could be trusted. "So, could you please answer my questions?"
Rider was being deliberately vague, not wanting to give the girl any information about what she already knew. After all, if she was truly Vanguard, she would already know, and if she were not then, the less she was told, the more likely she would be to make a mistake and reveal herself.