How to do a good okuri-ashi?

In your kendo guide for beginers (page 54) and video, you said no dragging for the back foot and the left foot can be lift up.

I don't understand because for me all forms of footwork (ayumi-ashi, okuri-ashi, hiraki-ashi, and tsugi-ashi) are performed with suri-ashi: sliding steps in which the feet never leave the floor.

Could you explain more when you write "no dragging in kendo footwork"?

Answer: If your feet are sticking to the floor when you move, you cannot slide/glide. This results in dragging.

If the soles of the feet are touching on the floor completely flat, you cannot even do suri-ashi.

These feet should be slightly lifted when moving. If suri-ashi is done correctly, you can feel dust of the floor rolling between your feet.

To move faster, we need to have as lees friction as possible between our feet and the floor. If you drag your feet, you are increasing friction.

Hope this explanation helps.