Bibin Renbōji hails from the Planet Sweets, where he holds the position of prince. He begins as notably carefree and somewhat lazy, frequently evading his royal duties and responsibilities. His playful and easygoing nature manifests in frequent naps and a strong preference for leisure.

Despite this initial reluctance towards princely obligations, Bibin reveals a core kindness and willingness to help others when genuinely needed. He forms significant relationships, particularly with the twin princesses Fine and Rein from another kingdom. His bond with Fine becomes pivotal to his journey, marked by support, shared adventures, and deepening affection.

Bibin pilots the unique Sweets Machine for transportation and occasionally in conflicts. He also exhibits musical talent, often strumming a guitar and singing. His design features distinctive gravity-defying blonde hair and a signature red-and-white outfit.

Throughout the narrative, Bibin undergoes substantial development. He gradually matures, learning to take his royal duties more seriously. While retaining his playful core, he becomes more reliable and responsible, especially when the safety of Fine, Rein, or others is threatened. His deepening feelings for Fine motivate increased proactivity and courage.

Bibin confronts challenges balancing his personal desires with his princely role. He learns the importance of reconciling his natural inclinations with royal expectations. His journey involves confronting threats to the Star Palaces and contributing to their protection, showcasing his growing commitment and resourcefulness. By the story's conclusion, Bibin emerges as a more dependable and mature individual, capable of fulfilling his responsibilities while maintaining his unique personality and strengthening his bonds.