Truth-Seeking Ball

Truth-Seeking Balls are spheres of malleable black chakra. Originating from the power of the Sage of the Six Paths, they are composed of all five basic nature transformations, Yin-Yang Release, and Six Paths Sage Chakra. They are capable of negating all forms of ninjutsu.

Usage
By utilizing "the power of the universe," the Truth-Seeking Balls can be shaped into a variety of forms, allowing them the flexibility to be used for offensive, defensive, and supplementary purposes. Obito Uchiha 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 wrap around the user to act as a defensive shield, or be launched to serve as high-speed projectiles. They are also capable of causing massive explosions by rapidly expanding in size.

According to Minato Namikaze, the balls are a type of technique that is always on standby, rather than activating 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, Obito's Truth-Seeking Balls did not nullify ninjutsu prior to him gaining control over the Ten-Tails' power. In the anime, the balls have also shown an ability to heal the user from damage.

The black substance 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. Obito used the black substance as chakra receivers, shooting them in six directions to perform the Six Red Yang Formation. The balls can also be used to create the legendary Sword of Nunoboko. When Kaguya summoned an enormous Truth-Seeking Ball, Black Zetsu referred to it as the start of a new dimension. 

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

Drawbacks
The user can only control the balls within 70 metres of their location, allowing opponents to separate them from the user by transporting them elsewhere. Hiruzen noted that there is likely a limit to the amount of time that the balls can take on another shape. After seeing the effects of Gamakichi's natural energy-imbued technique on Obito, Naruto and Tobirama Senju discovered that the balls are incapable of negating senjutsu. This was further proven when Naruto managed to land a hit on Obito while in Sage Mode. It was also shown that when the transformed balls come in direct contact with natural energy-based techniques, their form becomes disrupted. Additionally, the rapid expansion of the balls is capable of damaging the user's own body if they are not protected by other balls.

Similar to the chakra receivers, the balls will disintegrate if the user's chakra disappears. Any clones produced by the user will not have their own Truth-Seeking Balls. The clones can, however, have the balls passed on to them.

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.
 * In the original publication of chapter 689, Black Zetsu lists Wood as one of the component natures of Kaguya's Truth-Seeking Ball, rather than Water. Masashi Kishimoto confirmed this was an error in Issue #41 of Weekly Shōnen Jump, and stated that it would be corrected in the tankōbon release of the chapter.
 * Despite being a jutsu used by those who awakened the Six Paths Sage Technique, it is not categorized as senjutsu in the fourth databook.