The sudden appearance of someone that hasn't been there before, someone that he can't even see in the now-cracked mirror, is enough to startle him and instinctively take a step backwards before whirling around.

"Who the hell are you?" he blurts out, and he doesn't mean to come off as brusque as that probably will sound to Shima's ears. He's dreaming. He definitely has to be dreaming, even though he winces when his bleeding hand hurts and the sharp sting of pain tells him this is not a dream. People just don't have three eyes, and Yamato's also fairly certain that he looks way too human, way too real to even pass off as a Digimon. "Did you just come from--?" Vague hand gestures in the general direction of the trick space that Shima probably just stepped out from follows, and Yamato still sounds suspicious, wary.

Another wince, and another glance at the cracked mirror pulls out a few guilty feelings. "Eh. I was... startled," he finishes lamely. It sounds like an excuse. "I wasn't planning on breaking it?"

He would actually have offered to pay to replace the mirror that he's broken, but since the person at the admissions booth had taken most of his money earlier, he probably isn't going to have enough money to replace said mirror.