Mukuu Kekkai

Mukuu Kekkai ( 無空結界, lit. "Airless Barrier") is a Noble Art of Ouma Kurogane.

Description
Mukuu Kekkai is a passive wind based Noble Art. It releases a great amount of wind, and creates a powerful updraft, which initially obstructs the opponents vision. However, the techniques true purpose is to deprive the opponent of oxygen, drawing it up to the sky, limiting the amount of time they have to fight. The opponent has ten minutes before they completely run out of oxygen, and only one if they exert themselves by fighting.

Weakness
The area which is affected by Mukuu Kekkai is limited, although it is fairly large. Mukuu Kekkai also takes some time to completely deprive the opponent of oxygen.