must have been the wind

the user can turn their body into air for a short period of time (like logia)

the user can keep using this ability as long as he holds his breath, the moment the user exhales or breaths in he will turn back into his original form.

the ONLY way to train this technique is to increase lung capacity to hold your breathing longer

examples of use:

can be used to faze through attacks

can be used to get through small holes and cracks

can be used to fly while in air state

and can be used to gain speed (because air weighs a lot less so the user can use it for speed and then turn back to his normal form while keeping the speed)