Dust

This is my own AU that I'm creating called "The Useless"

The Useless: Is a fictional disease where once a person thinks the person they love/care for the most no longer needs them a 3 day countdown appears on their wrist. Once the timer hits zero they turn to dust. The only way to prevent dying once they get a timer is to find a way that that person needs them. Otherwise, they are "No longer necessary for the person's happiness". It's not hereditary and is more of a cognitive thing. Everyone in this AU is born with a "self-destruct" option so to speak. If their brain thinks that they're no longer useful it'll initiate the count-down.

In which Yamaguchi get's his timer during the match against Shiratorizawa.