Tokoyami

The Tokoyami are Mushi that exist in shadows and come out at night. It eats smaller mushi and people's memories. They also contain the Ginko.

Description
These Mushi species are created when living beings are exposed to the light emitted by the Ginko. When a living being is exposed to the light emitted by the Ginko for a long time, they turn into Tokoyami. This is also the how the Tokoyami came into existence.

If one is ever swallowed by the Tokoyami, first one must keep one eye closed and the other open. One may escape from this Mushi by using this method, but will only be able to remember one thing, such as a name, even if it isn't personal.

Plot
Before the start of the plot of the anime series Yoki, an 11 year old boy, was swallowed by the Tokoyami. He managed to escape, but only after being exposed to the Ginko thereby turning his hair white and one of his eyes green. Yoki was only able to remember one name, Ginko, which was the name of the Mushi within the Tokoyami. He then went by the name Ginko and became the protagnist of the series Mushishi.

Weaknesses
It has an affinity for Light.