|Family:||Mateo (Brother), Unnamed/deceased Grandpa|
|Friends:||Ash, Misty, Mateo|
|First Appearance:||OI007: The Crystal Onix!|
|Voice actor:||Tara Jayne (English)|
Marissa lives on Sunburst Island with her big brother Mateo. She helps him run a glass and crystal shop. Realizing that her brother needed the inspiration that her Grandpa once got from seeing the Crystal Onix, she decided to send out a message in a bottle to see if people would be able to help Mateo find it. The letter she wrote stated: "If you know anything about a Pokémon called the Crystal Onix, let me know right away." There are no record of Pokémon that she has owned or will own.