Mimily is a mermaid exiled from her ocean village after failing to fulfill her expected role as a princess, crucial for her race's continuance. A strange magical portal transported her away, trapping her in an underground waterway near a remote village. Her lonely songs echoed through the well, creating eerie moans mistaken by villagers for a haunting.

Cayna investigated these sounds, discovered Mimily, and freed her from the groundwater. Mimily found refuge in the village bathhouse Cayna built. There, she established a laundry business, utilizing her natural water manipulation abilities for washing. Despite Cayna's offer to help her return to the sea, Mimily chose to remain on the surface to run her laundry enterprise.

Physically, Mimily possesses long teal hair reaching her waist and bright green eyes. Her lower body is a turquoise, scaled fish-like tail. Distinctive webbed, fin-like ears project perpendicularly from her head, covered in blue skin and scales. She typically wears a pink fish-shaped hair accessory and a light cyan seashell bra. Beyond water manipulation, her characteristic mermaid singing voice initially caused the haunting rumors. Her documented story centers on establishing her life and laundry business within the village.