Truth-Seeking Ball

Truth-Seeking Balls are spheres of malleable black chakra composed of all five nature transformations and Yin–Yang Release. Each is about the size of a fist and hides within the power to completely obliterate a forest and to negate all forms of ninjutsu.

Usage
Once formed, these balls generally float in a circular formation behind the user's back. By utilising the power of, they can be shaped into a variety of forms, and the many natures comprising them can be combined to produce various effects. Obito usually shaped the balls by having them pierce through holes that temporarily formed in his hands, whereas other users forego this process and simply mould them. The balls can serve various offensive, defensive, and supplementary purposes, such as wrapping around the user to act as a shield, launching toward targets as high-speed projectiles, and causing massive explosions by rapidly expanding in size. The balls can also quickly heal severe injuries through contact, glowing red while doing so in the anime.

According to Minato Namikaze, the balls are a type of technique that is always on standby, rather than one that activates from nothing. Hiruzen Sarutobi stated that this technique uses attacks that instantly turn their target to dust, similar to Dust Release, but the technique's fluid nature allows it to serve both offensive and defensive purposes, and it can be maintained. Hiruzen also noted that, since the substance is a combination of more than three nature transformations, it is neither a kekkei genkai nor kekkei tōta, but greater than both. Tobirama Senju analysed that this technique can utilise Yin–Yang Release to nullify all ninjutsu the balls touch. As a result, any damage done by this technique to a reincarnated individual — who can usually regenerate infinitely — cannot be repaired, and said individual could die. However, this nullification effect does not appear to be automatic, as Obito's Truth-Seeking Balls did not nullify ninjutsu prior to him gaining control over the Ten-Tails' power. Naruto's Truth-Seeking Balls are able to utilise, which could effectively damage Madara's shadows.

The black chakra that comprises the balls is highly durable, only taking damage from powerful techniques such as the Evening Elephant and a senjutsu-enhanced Tailed Beast Ball. When Obito produced chakra receivers to use the Six Red Yang Formation, the ball behind his right hand emitted the same red chakra as the receivers and subsequently disappeared. The balls can also be used to create the legendary Sword of Nunoboko. 

Shape Variants
The balls can be manipulated into a variety of shapes for different purposes.

Drawbacks
The user starts with a set amount of balls and can only control them within 70 metres of their location, allowing opponents to separate them from the user by transporting them elsewhere. If they are somehow destroyed, or otherwise not retrieved by the user, they are permanently lost. Similarly, any clones produced by the user will not have their own Truth-Seeking Balls, though it is possible for the user to pass them over to a clone.

Hiruzen suspected that there is a limit to the amount of time that the balls can take on a particular shape. When the balls explode, they are capable of damaging the user's own body if they are not protected by other balls. After seeing the effects of Gamakichi's natural energy-imbued technique on Obito, Naruto and Tobirama discovered that the balls are incapable of negating senjutsu. It was also shown that when the transformed balls come in direct contact with senjutsu chakra, their form becomes disrupted. In the event that the user's chakra disappears, the balls will disintegrate in the same manner as the black receivers.

Trivia

 * The term comes from Mahāyāna Buddhism. The Kanji 求 means to wish for, while the  in Mahāyāna doctrine is to find the ultimate truth within one's own mind.
 * When a jinchūriki of the Ten-Tails gains control over the beast, the shakujō variant seems to instinctively form in their hand. Obito and Madara Uchiha each wielded one half of Hagoromo Ōtsutsuki's complete shakujō.
 * Despite the fourth databook stating that the Truth-Seeking Balls appear when one awakens the Six Paths Senjutsu, said databook does not categorise this technique as senjutsu. Kaguya, Hamura and Toneri have all made use of this technique without possessing the Six Paths Senjutsu.
 * Obito Uchiha was able to create a makeshift Truth-Seeking Ball out of Black Zetsu's black mass and shape it into a shakujō. Additionally, he absorbed some of Madara's Senjutsu chakra and applied it to the staff, making it invulnerable to Madara's own Truth-Seeking Balls.
 * In Naruto Shippūden: Ultimate Ninja Storm 4, the Truth-Seeking Balls are purple.