|This is part of the Sky Pretty Cure Series!|
|Season||Sky Pretty Cure|
|Debut||Sky Pretty Cure: Kyūjitsu ni Soragawa|
Marcasite is an ancient monster of Skyriver, who has attacked the lands many years ago. Marcasite is a demon of water, who controls the power of liquid waves. In his liquid form, Marcasite can shallow people who get too close to the surface of the water. These people are brought to a subspace of darkness. The people and creatures who get captured by Tanbaga also end up in this space of dark. In his manifested form, Marcasite can attack with his elemental powers and also protect himself from attacks.
- Even though Marcasite is considered as male through out the series, his gender has never been confirmed. This might mean that Marcasite and Tanbaga are the only creatures in the Sky Pretty Cure Series to have no gender.
- Marcasite and Tanbaga are the second demons to appear in the Sky Pretty Cure Series, preceded by Catastrophe.