Board Thread:Questions and Answers/@comment-18812574-20150614041041/@comment-2182964-20150614094705

Regarding how a Shinigami does affix the reishi beneath their feet, it was inferred a few chapters ago if I remember correctly. Kenpachi Zaraki I believe. He never demonstrated the ability to stand in the air like other Shinigami until after he had his beat-down with Unohana. He was stronger after this event, with greater control of his spiritual power to boot, so it may actually be an expression of the Shinigami's control of their own power? He clearly stands in the air during his battle with the vision-dude. I don't know though, I'm only guessing.