The term Mikiri is used to describe cutting the distance with your body.
The word Mikiri itself means body cut. Mi (身) means body and Kiri (切り) means cut. Of course this is a figure of speech meaning that you use your body to cut the distance.
The word cut implies that it is a sharp movement. A split second in time. Mikiri is pulling the body sharply, just out of range of the attack.
Doing Mikiri by moving out of range is the easiest of these three. Still difficult to pull of, but the easiest one nevertheless.
Just step back is not Mikiri.
Just slide back is not Mikiri.
It's Mikiri if you use the right distance and time it correctly.
Don't just lean, you'll get hit. If you want this to work you need to apply 3 keys to your movement which I explain in the video.
The key to absorb and be successful doing so depends on a couple of things. To be precise: one in particular. Timing.