Dr. Komyogi is an expert in robotics and has a wealthy sponsor, Herbert Gill. Gill however, is a horrible man who forces Dr. Komyogi to develop numerous robots which he plans to use to take over the world. Dr. Komyogi realizes Gill's dark ambition and secretly develops a high-performance humanoid-robot called Jiro, who looks exactly like a human but transforms into a battle robot Kikaider who has his great superpower. Komyoji leaves Kikaider with his daughter Mitsuko and then disappears. Finally, Gill makes his move. He unleashes a robot army named Dark to dominate and control human society. Mitsuko, reading a message left for her by her father Dr. Komyogi, persuades Jiro/Kikaider to fight off Gill's terrible robots. On that day, Jiro/Kikaider's fierce battles with Dark begin! (Source: Comixology)

Thirty years ago, fallen gods and fallen towers suddenly appeared across the land. Monsters poured forth from the fallen towers, destroying the world's peace. In response, all the gods above bestowed sacred weapons upon outstanding humans. Heroes who rose to reclaim peace by conquering the towers and purifying the fallen gods. Among them stood an unmatched warrior named Shotaro Kusunoki, wielder of the 'Exorcising Blade,' was hailed as one the Three Great Heroes. Watching his brother's legendary feats from the sidelines was Hiromu Kusunoki, a lowly baggage carrier who longed to see the day peace returned. However, fate took a cruel turn when the fallen god Futsunushi possesses Shotaro's body, turning him into a vessel of darkness. On the brink of death, Hiromu hears a mysterious voice call out from the Exorcising Blade. That voice is Gayamaru, the mighty god sealed within the blade. To save his brother, the boy forms a pact with the mighty god, and together, they will climb to the peak of power and overcome darkness itself! The curtains rise on a modern battle fantasy of gods, blades, and the bonds between brothers!