Coopy is the designated support fairy for Yamaneko Arthur within the franchise. Her appearance features heterochromia, a distinctive hat, and functional fairy wings.

Her personality presents an airhead demeanor, but this is a deliberate act masking her true nature. She exhibits a protective streak towards Yamaneko Arthur, actively taking charge of her care. Simultaneously, Coopy harbors a competitive rivalry with Arthur, driven by her ambition to be recognized as the "cutest."

Specific interactions showcase her traits: she visibly blushed when seeing Dancho Arthur in a pink apron, unlike others present. In combat, she threw herself defensively in front of fellow fairy Bodach to block an Aqua Ball attack launched by Arthur Aqua. Her established role centers on her dynamic with Yamaneko Arthur and her actions within group contexts.