Turns into mist

Kojou solemnly raised his voice. “Kojou Akatsuki, heir to the bloodline Kaleid Blood, releases thee from thy bonds…!”
The mist that enveloped him grew even thicker. Kojou himself was transforming into mist.
“C’mon over, Beast Vassal Number Four, Natra Cinereus—!”
Finally, mist covered the entire building; the contours of the entire world grew vague. Silver chaos blotted out buildings, people, the air itself—everything.

...

Yaze nodded at her. “The cliché is for vamps to turn to mist and run from battle, not to turn a whole island into mist. Thanks to that, we’ve been saved this time around…but…”
“It proves all over again that he could wipe this island off the map at any moment he pleases, does it not?”
The boy seemed to suppress his own feelings on the matter as he gave a sober scoff. “Hmph. Was this part of your plan, too?”
A short time earlier, Itogami Island, robbed of its magic, had been on the verge of collapse. But now that everything had been turned to mist, gravity ceased to affect it; since there was nothing solid, the strength of the materials holding it together was no longer a concern. Perhaps it might be said that one could not destroy that which was intangible.