A Haishaku is a microscopic yokai that resembles a tiny monster in the vague shape of a cloud.
It starts by infecting a victim's armpit then quickly makes its way into their lung and causes their skin to become abnormally white and smooth.
They also cause a victim to develop an aversion to all smells except that of raw fish and the victim will also fall into deep depression and pessimism, with unconditional crying that causes "tears to flow like rain".