Rigel debuted as the protagonist's friend and rival in the 1991 anime adaptation of *21 Emon*, created exclusively for the series and absent from Fujiko F. Fujio's original manga. He completes the central trio alongside 21 Emon and Luna, appearing consistently across all 39 episodes. Functioning as a dynamic counterbalance to the protagonist, his interactions with 21 Emon blend camaraderie with competitive tension.

Rigel's background, origins, and personal history remain unspecified in existing sources. The series does not explore his character development or dedicate narrative arcs to his growth, with his role primarily amplifying group dynamics. His underlying motivations and deeper personality traits are not elaborated upon in official material.

Though the crossover film *21 Emon & Doraemon: Welcome to Hotel Tsunesha* includes other series characters, Rigel is absent from its narrative. His documented involvement remains strictly limited to the 1991 anime, with no recorded appearances in spin-offs, OVAs, or related media.