This is one of many variations of the Chidori that uses shape transformation. In comparison to the standard Chidori, it further specialises in speed, by being transformed into countless sharp senbon, which are all aimed and fired at the enemy. By increasing the amount of chakra used, the number of senbon also increases proportionally. When used in tandem with the Sharingan, it becomes far more effective and deadly, as it allows the user to precisely shoot for the target's vital points.
After attaining chakra from the nine tailed beasts, Sasuke's new Susanoo was able to produce large senbon capable of countering Naruto's senjutsu-enhanced tailed beast balls.