Six Paths Yin Power (Seireitou)

The Six Paths Yin Power is a sealing mark adorned by an individual in order to invoke the highest degree of Yin Release. It was first stumbled upon by Hagoromo Ōtsutsuki, its inventor, who discovered the method after thoroughly studying his mother's abilities. He then passed on the knowledge of the seal to his elder brother, Hamura Ōtsutsuki, who used it together with his brother in the sealing of Kaguya. It is represented by a dark-colored, crescent moon-like marking on the user's left palm.

Overview
Yin and Yang are the absolute dual forces in the universe. Everything rises and falls with them in perfect harmony. One gives birth to the other and vice-versa, establishing a perfect balance. It is because of their existence that creation was allowed to progress, causing the iron hold of primordial darkness to vanish from the ruling seat. Yin's role is the creation of form and shape, representing the spiritual energy of the dual energies that compose chakra.

Hagoromo Ōtsutsuki used this power in conjunction with his power of Yang to create the nine tailed beasts through the Creation of All Things technique. In order to separate the chakra of the Ten-Tails following the sealing of Kaguya Ōtsutsuki, Hagoromo applied his Yin power to divide the Ten-Tails' form into nine individual species with unique shapes, which were then given life by his power of Yang. Form is what allows consistency in the universe to exist. Without it, there can be no existence. Life itself cannot maintain itself without holding onto a form; otherwise it will expand and spread out until none of it remains. But form and shape can be described in a variety of ways. It can be defined as direction, in which a flow of energy — the flow of life — follows and must keep to; otherwise it will all fall apart and be rendered asunder. All of life follows a flow and all things in the universe possess a shape in which life becomes possible. Life must follow form, that is the way it has always been. And when form changes, so too does life. It is the way of the universe. Hagoromo understood that the Ten-Tails, as it was, was a form created from hatred. In his pursuit of peace, he separated the hate-forged beast into nine new beings, hoping that if a form was created with a pure intent, so too will the life that fills that form reflect upon that idea. When wielding the shaping force in one's hand, the seal will glow a bright blue and emit a bluish radiance in the form of flames that represent the shaping force in one's hand.

While he did not bear the actual seal but did in fact gain the power of the Sage himself after becoming the jinchūriki of the Ten-Tails, a fragment of Hagoromo's Yin ability was displayed by Madara Uchiha. He revealed that with the form-creating powers of Yin, it was possible to manifest elemental natures and manipulate them in accordance with one's will. In his senjutsu, the lightning that was manifested was strangely controlled for standard electricity; shaped into actually solid pathways of lightning that spread outwards and followed Madara's whim. Its solidity was confirmed when Naruto Uzumaki managed to stop its progression by throwing a rod-shaped Truth-Seeking Ball at its path; interrupting its shape and direction which caused the technique to fall apart.

However, it was Sasuke Uchiha that showed the true extent to the Yin power's shaping methods. By applying it to his Chidori, the coloration of the bluish-white electricity technique became a jet black as its shape became more focused. Lightning Release, which already carries the power of enhanced cutting due to increasing the vibrations within one's chakra, was now further refined under the influence of the Yin power, allowing Sasuke to actually bisect Madara at the waist while the latter was empowered as a jinchūriki. It then allows one to infer that the Yin power, when taken to its extreme, allows its user to not only provide shape to power and energy but also to further refine an existing form using its shaping methods. Water Release could become more vicious and thick, while maintaining its fluidity, in order to send an opponent to an abysmal fate. Fire Release can be refined to only burn specific targets while later being willed to cease burning. In fact, it is presumed that the Amaterasu of the Uchiha clan was first created by Indra, who could invoke the Yin powers of his father; given its coloration and its precision and accuracy when basic degrees of shape manipulation was applied. Wind Release can be fashioned into graceful currents that can act as airborne blades. Earth Release can be fashioned into intricate structures but can also be altered in order to bring out the sediments within them in order to create a pure substance.

After being granted the mark of the moon by Hamura Ōtsutsuki, Seireitou Hyūga demonstrated another aspect to the power of Yin power that allows one to actually target a victim's mind, as it is the brain which houses spiritual energy and is subjected to it; the cause of which gives birth to most versions of dōjutsu, such as the Sharingan. The mark of the moon influences spiritual energy, which exists within the mind, and therefore, influencing the spiritual energy is akin to influencing the mind of the victim. The seal allows an individual to force the mind of a victim into a comatose state. However, the true danger in this is that the victim's brain would be forced to shut down particularly important functions such as control of their central nervous system; leaving them exposed to a variety of subsequent conditions. It can also shut off the flow of spiritual energy and subsequent special chakra within the brain that enables dōjutsu, essentially forcing said visual techniques to be shut off as long as the Yin power's influence remains over that victim.

As noted by Black Zetsu, there is a special resonance between the Yin and Yang powers, allowing the wielders to sense each other's presence but also to connect chakra together even when split apart from a distance; as demonstrated by Seireitou and Ryun Uchiha. When the Yin and Yang powers are used together, they can transform their target into the core of Chibaku Tensei. The process of how this happens was elaborated upon by Seireitou. Yin rules spiritual energy while Yang rules physical energy. When the palms close, the users are capable of enacting their will over the opponent. And in doing so, they can forcefully manipulate their chakra, which is composed of those dual energies and are subject to the twin forces, allowing them to convert their chakra into gravitational waves that turns them into the core of the original Chibaku Tensei technique while also ripping away chakra from their form, which leads to their sealing. In essence, Yin alters their form in relation to the universe, which causes them to become the core of gravity, while Yang manipulates their life force and rips away chakra from them. Both seals were designed to target specific energies within the target's body upon coming into physical contact with them. The Yin Seal targets the opponent's spiritual energy, the origin of all dōjutsu, while the Yang Seal targets the opponent's physical energy, that which is present in the cells of all living beings and allows for the use of one's muscles. When both energies are overtaken by the seal, the victim's chakra itself can be manipulated and the users' wills can be imprinted onto their bodies for the fūinjutsu.

Hagoromo's unique staff, which is a perfect application of the Truth-Seeking Ball, bears two separate and different staff ends; each possessing unique ornaments which represent Yin and Yang respectively. Madara was only capable of wielding the Yin portion, which was proven by the fact that he could only manifest the Sage of Six Paths' staff with only one ornament.