When the player and other Pokémon explore the Glacier Palace for the first time, they discover floating ice crystals, at this point it was a mystery. The Bittercold was first mentioned by Hydreigon after escaping from Munna's gang while conversing the player the gang's motives, this moment explain the reason why floating ice crystals appear when the player recall their memories in the Glacier Palace. Hydreigon told the player that they must destroy the Bittercold. Later in the story, it was revealed that Kyurem guards the Bittercold to protect it's future, which would lead to the end of the world.