[Mika is confused by the idea of being in another world, that there are others from different ones and silently he attempts to figure it out. It doesn't quite seem like when they were taken from the surface down into the underground city but that's the only thing he can compare it to at the moment.
Well, the only real thing that's ever happened to him.
Even if there was something Mika was going to say in response to the explanation of the world or how many vampires are about it all gets caught in his throat when the words "vampire hunter" hangs in the air. His eyes widen and he stares straight at Zero, his heart threatening to pound right out of his chest as a voice internally screams "he knows!" inside of his head.
Blue eyes dart to the back of Yuu's head and he almost chokes on a lump that formed. That's when Mika drops Yuu's arm and steps back three times - away from Zero and away from the other boy.
He's a vampire and that's a vampire hunter. That man is here to kill him and Mika won't let Yuu get hurt in the process. Finally he finds his voice.]
P-please. Don't hurt him. He's not... [Tears spring up anew.] It's not Yuu-chan.
[The admittance is firm, defiant even. Defying the hunter to challenge the claim when Mika is speaking the truth.]