Six Paths Yang Power

The Six Paths Yang Power is a tattoo that was created by Hagoromo Ōtsutsuki and part of a powerful sealing technique.

Background
By utilising the Yang Release within the seal, Naruto can heal others from otherwise fatal and untreatable conditions: such as halting the effects of the Eighth Gate on Might Guy, restoring Kakashi Hatake's missing eye, and resuscitating a dying Obito Uchiha. This ability, however, does have its limits, as showcased when Sakura Haruno acknowledged Obito's eventual demise even after the latter was seemingly restored by Naruto's initial attempt at saving his life. Not only that, but Naruto was also unable to heal the effects of Kaguya's All-Killing Ash Bones technique on Obito, albeit was still capable of slowing down its effects long enough for the latter to voice his final farewells.

It has also been noted by Black Zetsu that there is a special resonance between the Six Paths Yin and Yang powers, making it easier for the wielders to sense each other.