Cachito, known as Tink in the original Japanese version, is a young angel-in-training whose mischievous act during the divine ceremony to determine Sapphire's gender sets the story in motion. He causes her to swallow both a boy's blue heart and a girl's pink heart, resulting in her birth with both male and female attributes. As punishment, God sends him to Earth to retrieve the extra heart and correct the celestial error.

On Earth, he forms a close bond with Sapphire, who refuses to give up her boy's heart. This leaves him stranded in a mortal form without divine powers, retaining only the ability to blow a trumpet loudly – a sound effective against supernatural foes like Satan due to their fear of angels. Though brave, his impulsive nature often leads him into physical confrontations where he suffers injuries.

He remains Sapphire's loyal companion throughout her struggles to maintain her dual identity and protect her kingdom. He aids her in thwarting schemes by antagonists like Duke Duralumin and Baron Nylon seeking to expose her true gender. His presence proves crucial during confrontations with darker forces, particularly Satan, who covets Sapphire's unique two-hearted soul.

His character arc culminates in the anime series' finale. When Sapphire's parents are killed during the conflict with the tyrant Mr. X, he makes a pivotal sacrifice: offering his life to God in exchange for their resurrection. This selfless act results in his mortal death, allowing the King and Queen to return to life. His spirit ascends to heaven, where he finally earns his wings as a fulfilled angel.

The character does not appear in stage musical adaptations or later manga remakes, such as the 1967 illustrated version by Kitano Hideaki. His narrative remains consistent across the original manga serializations and the 1967-1968 anime adaptation, with no significant variations in spin-offs or sequels like *The Twin Knights*.