This is an "addition-line ninjutsu" that augments the cutting power of a bladed weapon by flowingchakra into it. A dense blade of chakra is formed around the physical blade, extending its reach. Because users can adjust the length of this chakra blade at will, opponents can never fully anticipate the user's attacks.
Asuma performs the Flying Swallow with his unique Chakra Blades. He furthermore prefers using wind chakra so that his blades become sharp enough to cut through stone or metal.
The Flying Swallow is a piece used in taikyoku shōgi, a variant of the standard shōgi with over 400 pieces.
Although Tō no Sho classifies Flying Swallow as taijutsu, its actual entry describes it as ninjutsu.
In the Naruto: Ultimate Ninja series , Kakashi's midair taijutsu attacks are named "Flying Swallow", "Rising Swallow", and "Falling Swallow". When Asuma became playable in Naruto: Ultimate Ninja 3, the Japanese version of the game used "Flying Swallow" in both Kakashi's and Asuma's movesets; in its English translation, Asuma's move is instead called "Flying Sparrow" to avoid confusion.