Pokémon #562 in National PokéDex, a Ghost type Pokémon.
Yamask is a shadow-like Pokémon holding a mask that has a face from its time as a human. It has two shadowy, tendril-like arms and large, red eyes. It also has a small tail-like appendage that holds the mask.
It evolves into Cofagrigus.
Japanese Name: Desumasu