As Eiro pushed the Crow againt the wall, this Monster said something that Eiro didn't expect at all. He turned his head to the side for just a moment, getting a glance at a figure standing far in the distance in the middle of the air. And he wasn't flying with something like wings, he was really just standing there, as if levitating.
And it was really just for a moment, and Eiro didn't loosen up the grip he had on the Crow either. But when he was in the process of turning his head back toward the Crow, he could feel the literal lack of mass in front of him. Eiro dropped forward a little and tried to collect himself as he realized what was going on.
The first thing that Eiro realized was that there was no way that the Crow actually just ran away. Eiro would have been able to notice it in one way or another, whether by seeing it, hearing its footsteps, or even just by feeling the wind that it pulled with it.