Sakura and Shirou
Shirou nodded.
"Nice to meet you, Ellen", he said, before returning to the topic.
"Yes, you are correct, of course, but the girl claimed she was a demon, and she can fly and seems to have some kind of mind-altering powers, so it's a good hypothesis, at least", he said.
Before he could add more, though, Sakura suddenly recoiled in shock.
"What's wrong?" he asked, obviously concerned.
"I.. I don't know, exactly, but my familiar was destroyed. The target reacted in a way which basically confirmed the girl's suspicions, and then a laser-like beam suddenly appeared out of nowhere and shot towards the familiar. Then, the connection broke", she said, obviously worried. "I think she's dangerous, Senpai."
Shirou nodded in agreement, before turning to the newcomer.
"Well, we don't know much about her either, honestly", he said, figuring that there was no reason to hide information about their target. "We were just checking out the mana signature, but it seems like she detected my wife's familiar and destroyed it."
"Well, Senpai, what should we do now?" Sakura added. "She seems dangerous, her laser looked powerful and she can fly and, seemingly, control people's minds. But, spying on her is going to be difficult, especially when she's indoors."
A thought crossed Shirou's mind.
"How good are your senses?" he said to the new girl. "I can see a long distance with my magic, but I can't hear things over this range. Since Sakura's familiars seem to be too easy to detect, perhaps you can help."