Corail holds the title of Prince of Coralia in the Country of Coral. His background instills a deep duty to protect coral reefs and marine life, seeing this as central to his princely role. He radiates cheerful innocence, though flashes of an impish or devilish side occasionally surface without his conscious awareness. Physically, he possesses red hair, animal ears, fin ears, stands 161 cm tall, and frequently wears a circlet.

His interactions often involve guiding others to appreciate coral ecosystems, blending enthusiastic sharing of their beauty with a protective stance against threats like pollution or resource exploitation, leading him to declare battle against ocean polluters. Relationship dynamics evolve from playful invitations for hand-holding or exploring sunken ships toward deeper emotional connections. These later expressions include commitments like desires for future togetherness, marriage considerations, embracing during sleep, and requests for kisses, sometimes causing flustered reactions.

Two distinct relationship paths emerge: one emphasizes mutual happiness and admiration ("Sun" route) featuring confident declarations of affection, while the other focuses on protective devotion ("Moon" route) prioritizing the other's safety and seeking exclusive attention. Both routes underscore his inherent loyalty and capacity for profound emotional bonds. In combat, he utilizes specialized skills named after coral varieties, typically erasing specific bead rows on puzzle boards to fight dream-consuming enemies. His sea connection allows him to grant others underwater breathing.

Throughout his story, core traits remain constant: unwavering dedication to coral conservation, a bright demeanor interwoven with subtle mischief, and deepening emotional connections within key relationships. His development primarily reflects growing openness about affection and commitment rather than fundamental personality changes.