"A cat?..." Kei knows what a cat is. He was on Earth long enough for that. This person looked nothing like those. "I apologize for not realizing. You don't look how I expected."

He's not bothering to address the matter of what a Sturm is just now. It's enough that it wasn't recognized. Although the response is irritable, Kei responds calmly - it doesn't seem directed at him, exactly. "Would you like a hand? You seem unaccustomed to pets."