Teinen

Teinen (停年, "Age Limit") is the biological anomaly found in members of the Sōzō clan that triggers the eventual process of death in their bodies as a result of the Earth's atmosphere and environment. This is because the Earth's terrestrial chemicals are much more crude and corrosive than what it is found on Ninjin. Some have overcome this illness by eating the Human Faced Fruit which grows from a tree that is fed the blood and life force of those buried alive.