Coupy acts as the energetic and playful fairy companion to Yamaneko Arthur, primarily supporting him during missions. She demonstrates notable expressiveness, such as responding with noticeable blushing when Dancho Arthur wore a pink apron, a reaction distinct from other Arthurs and fairies. She also displayed protective instincts, placing her hands behind fellow fairy Bodach to shield him from an Aqua Ball attack by Arthur Aqua. Coupy possesses yellow or blonde hair and multicolored eyes. As Yamaneko's dedicated fairy, she operates among other fairy companions assigned to the Arthurs; her background and development in other media are not detailed in the provided materials.