When Astro is activated the city's power starts to drain, and he must try and stop the robot Magnamite from destroying everything. Armed with Kokoro (the ability of free will) Astro discovers his purpose for being activated.

The evil Skunk tricks Denkou, an "Invisible Robot," into committing a string of robberies. Astro soon realizes that Denkou is not bad, she just doesn't know the difference between right and wrong and Astro is the only one that can teach her.