Kotaro Minami and Nobuhiko Akizuki were born on the day of a solar eclipse. Kotaro was adopted by Nobuhiko's parents after his own parents were murdered by the cult organization "Gorgom." On their 19th birthday, Kotaro and Nobuhiko are abducted by Gorgom and converted into cyborgs, codnamed "Black Sun" and "Shadow Moon," respectively. The two would be candidates for the cult's new Century King, but with the help of his foster father, Kotaro escapes from Gorgom before the organization brainwashes him. Under the name Kamen Rider BLACK, Kotaro wages war against Gorgom to protect Japan and save Nobuhiko.
