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.
Due to being a human long ago, it has memories of being a human. If someone wears the mask Yamask carries, they will become possessed by the Yamask in question. Sometimes, it looks at this mask and cries, apparently in longing. Yamask is known to wander the ruins of ancient civilizations.
Yamask made an appearance in A Night in the Nacrene City Museum!, where it was causing havoc in the Nacrene City Museum because its mask had been put on display after it accidentally dropped it while sleeping. In the end Lenora, along with Ash, Iris, Cilan and Hawes gained an understanding with it and gave its mask back and Yamask left the museum peacefully.
Yamask's base Speed is the same as that of its evolution.
No other Pokémon has the same Egg Group combination as Yamask and its evolution.
Origin
Yamask is based on an Egyptian Ba holding a death mask.
Name origin
Yamask may be a combination of 闇 yami (darkness), や ya (bad), or Yama (lord of the dead in Hindu and Buddhist mythology), and mask.
Desumasu may be a combination of death and mask. It is also a pun off of ですます体 desumasu-tai, a form of polite Japanese which gets its name from the fact that sentences often end in です desu or ます masu.
This Pokémon article is part of Project Pokédex, a Bulbapedia project that aims to write comprehensive articles on each Pokémon species, as well as Pokémon groups and forms.