Kageoni

is a technique of Shunsui Kyōraku's Zanpakutō, Katen Kyōkotsu.

Description
The loser of this game is whoever gets their shadow stepped upon. The game itself allows competitors to manipulate shadows to their advantage: Shunsui has hidden himself in shadows by using this technique, and he can control the shadows and use them to attack an opponent by attacking the shadow which they are currently standing upon. Shunsui can also create a pocket dimension inside the shadow of another person, within which he can hide himself and others; those in this pocket dimension can exit from shadows of any size freely as Shunsui does.