Black Receiver

Black Receivers are black rods that function as demodulators for high-frequency chakra signals. Users are able to create and transmit their chakra into these receivers for a variety of purposes.

Origin
Black receivers are said to be a trademark of the Rinnegan. Wielders of the dōjutsu are able to generate the rods from their own bodies, usually from the palms of their hands. However, there have been several instances in which black rods were produced through other means:
 * While connected to the Demonic Statue of the Outer Path, Madara Uchiha produced a black rod from Hashirama's artificial body and identified it as a physical manifestation of his will. He then told Obito Uchiha to use it when performing the Six Paths Technique.
 * Black rods have been seen protruding from the Demonic Statue's midsection at times. On one occasion, these rods pierced Nagato's back and drained him of his life force, which allowed him to control the statue.
 * Black rods have sprouted from Obito's artificial right half on several occasions: upon first awakening his Mangekyō Sharingan and using Wood Release, when Madara used the rods to control his actions, and when Black Zetsu first coated his body and forced him to revive Madara.
 * When Obito was the Ten-Tails' jinchūriki, he converted one of his Truth-Seeking Balls into six black receivers, which he used to activate the Six Red Yang Formation.

Usage
Black receivers are formed out of chakra, which takes on a consistency similar to metal. They are durable enough to break steel scalpels, as well as sharp enough to pierce through human bodies with ease. Though durable, the rods can still be destroyed when struck with sufficient force, and their creator is able to break them apart without any apparent difficulty. Once formed, the user can transmit chakra to these receivers from across vast distances, though for best results, they must be nearby and at a high elevation. Though chakra being sent to these receivers can be sensed, a skilled user can prevent their location from being discovered by constantly changing the frequency of their chakra. Offensively employing receivers from afar carries a risk, as those with sensing capabilities can trace the transmitted chakra back to the user when pierced with one. When receiving chakra, the black rods noticeably heat up.

By stabbing an opponent with the rods, the user can transmit their chakra into the target's body, disrupting their own chakra and throwing off their movements. The user can fully immobilise the target by stabbing them with multiple rods, as well as prevent them from moulding additional chakra by piercing their tenketsu. Provided the user is close enough, they can potentially control the target's movements, though this can be resisted if the target's own chakra is powerful enough. Aside from being stabbed, simply touching the receivers can apparently also incur negative effects, though Rinnegan wielders are seemingly immune.

Chakra receivers are also used to control the Six Paths of Pain: six reanimated corpses that possess copies of the Rinnegan, granting them a shared field of vision with their creator. Nagato controlled his Six Paths of Pain using numerous receivers fashioned into piercings, which were implanted all about their bodies, whereas Obito had a single rod implanted in each body's chest. Among other Rinnegan abilities, the bodies are capable of producing additional rods to serve as weapons. As they are controlled by the user's chakra, opponents can prevent these bodies from moving by removing all of their receivers. The receivers implanted in Obito's Six Paths of Pain doubled as a means of temporarily binding the chakra of the tailed beasts sealed inside the Demonic Statue to their bodies, making them into jinchūriki. When they entered Tailed Beast Mode, the receivers would relocate from the jinchūriki's chests up to the tailed beasts' necks. The creatures Nagato summoned through the Animal Path were also embedded with numerous receivers, suggesting he controlled them in a similar manner.

When employed offensively, the black rods make for effective weapons. They can emerge from the user's hand to stab opponents, be broken off and wielded like swords, or be launched as high-speed projectiles, and the size and shape of the generated receivers can be adjusted to fit the situation. Obito is shown employing black receivers fashioned into giant stakes as projectiles, ejecting them from Kamui's dimension to pierce and pin targets. He can also manifest chakra chains to bind those touching the receivers with an even greater binding power. In the anime, the user can also apply shape transformation to the rods after launching them, altering them into more elaborate forms.

Black receivers disintegrate when their creator is killed or similarly incapacitated, alongside any Truth-Seeking Balls they may possess.

Trivia

 * Obito implied the binding power of the black rods is related to the Outer Path. However, Madara was able to use their binding power even after losing his Rinnegan.
 * Similar to Truth-Seeking Balls, black receivers appear to hinder the regenerative qualities of Impure World Reincarnation to some extent, as the wounds of reincarnated individuals do not immediately heal while the rods are pierced through their bodies, though they do eventually heal.
 * Naruto Uzumaki used something similar to black receivers when he shaped his Truth-Seeking Balls into rods and used them to immobilise Madara and Black Zetsu.
 * In Naruto Shippūden: Shinobi Rumble, Pain's Black Needle Stab temporarily reverses the controls of those stabbed by his black rods.
 * Isshiki Ōtsutsuki has employed similar tools, however they're different in that Isshiki has no Rinnegan, and they function different. Isshiki's rods are not grown from his own body, being manipulated in size and retrieved from storage, and they absorb chakra instead of Isshiki transmitting his own to disrupt the chakra of those it pierces.