Rayleigh and Ash have been friends since they were very young. Rayleigh's mom is a Pokémon scientist so when she was young, she visited Pallet Town a lot for her mom's work. They went on every adventure together and worked with Goh at Professor Cerise's lab. One day, the three along with Chloe went into a forest by Rayleigh's hometown that was said to be haunted. When in the forest Rayleigh ends up disappearing before her friends' eyes. She ended up in a strange world so different from hers.