Inochigakede - At the Risk of LifeEdit
Inochigakede is a medical ninjutsu that isn't widespread throughout the lands due to the initial risk that it has. The user first must have someone else help them remove their eye, then inscribe a seal on their eye, then replace it back. For the two weeks following, the user isn't allowed to use the eye for anything. The seal allows the user to see a constant ring around everyone that they look at's neck. The ring is normally pure white, but as they start losing health or become sick, the ring turns to a gray color. The darker the ring, the closer to death they are, until finally the ring is black, which indicates that the person is dead.