Astro Boy (1980)

S1E3 The Robot Circus

Toby finds himself trapped under the control of a robot circus owner, forced to perform hard labor. During his time there, he forms a friendship with a young circus employee named Kathy. When Dr. Boynton's colleague, Professor Elefun, arrives to rescue him, the ringmaster outright denies his release. It’s then that Toby is given a new identity, "Astro."