Cologne was the fairy partner to Tsukikage Yuri during her tenure as Cure Moonlight, dedicated to safeguarding the Tree of Hearts. His appearance featured a white body adorned with distinct, sharp, light purple heart-shaped markings above slanted eyes, echoing the sharpness of his tail and bangs. He possessed small light purple and white ears, a sharp silver ornament on the left side of his head, and a sharp purple neck ornament bearing an attached silver heart.

Personality-wise, Cologne displayed maturity and calmness beyond other fairies. He held deep concern for Yuri's well-being, understanding the dangers she faced as a Pretty Cure while respecting her resolve. He regarded the junior fairies Chypre and Coffret as proteges, adopting a protective older brother role toward them.

Cologne's history with Yuri began when he discovered her latent power at Hanasaki Kaoruko's botanical garden during his search for a partner. Despite Kaoruko's objections, he revealed himself to Yuri after a week of observation, explaining the threat posed by the Desert Apostles, the vital significance of the Heart Tree, and the Pretty Cure mission. Yuri accepted the role, driven by her quest to find the Tree of Hearts and her missing father, whose disappearance connected to her mother's transformation into a Desertrian. Throughout their partnership, Cologne advocated for recruiting additional Pretty Cure allies to support Yuri, though she initially refused.

Cologne met his end during a battle against the Desert Apostles. As Dark Pretty Cure attacked and Professor Sabaku targeted Cure Moonlight, he sacrificed himself by intercepting a lethal projectile meant for her. He vanished in Yuri's arms, an event that profoundly impacted her and contributed to her temporary loss of Pretty Cure abilities.

Following his death, Cologne's spirit endured, watching over Yuri unseen and unheard. Once the Heart Pot gathered sufficient energy, his spirit manifested visibly. He guided Yuri to the Tree of Hearts, affirming her strength and kindness and noting her newfound friendships. This encouraged Yuri to reclaim her Cure Moonlight identity to aid the new Pretty Cure team. During Cure Moonlight's final battle against Dark Pretty Cure, Cologne's spirit provided vocal encouragement, reinforcing his enduring presence. After her victory, he expressed confidence in her recovery and the healing of her Heart Flower before fading away permanently.

Cologne possessed abilities including the capacity to perceive human Heart Flowers through focused concentration. He supplied Yuri's Pretty Cure Seed for transformations and could fly. His name derives from the perfume type, referencing a concentration of fragrance oils typically associated with lighter scents.