A strange old woman allows a teenage runaway and a young orphan to stay in an abandoned house that overlooks the sea. However, when a menacing entity threatens their new home, they must band together and face their fears to save it.
Ide is convinced that a female agent dispatched from headquarters in Paris isn't who she appears to be; his suspicions prove correct when she reveals herself to be a member of a race of subterranean humanoids bent on enslaving the Earth's surface.
A wild gang of robots rampage through the city; Uran tries to teach Jump how to do tricks; disguising himself as a dog, Astro sneaks out to search for the Robot Vikings.
Astro receives a message in a bottle from captives held in an undersea mining station and heads off to rescue them, but first he must tangle with an ocean monster.
Uran sneaks into the venue for the Robotics Championships, takes part in a match and defeats a player, but Daddy Walrus refuses when the promoter scouts for her.
The Ancient One helps the heroes reach Talpa's castle and the team faces the combined might of the dark forces in an attempt to break through and face Talpa himself.
With the powers of all the other armors at his command, Talpa confronts Ryo, the only remaining warrior, who must find a way to defeat Talpa without destroying his captured friends.
As Ryo fights to keep Talpa from absorbing him into his armor, the Ancient One tells Ryo about Talpa's origins and helps Ryo understand the armors can be used for good as long as the heroes stay determined to fight against evil.
Despite vanquishing Talpa and restoring the city and its people, the heroes remain unsettled due to the lingering evil forces and the toll the Inferno Armor is taking on Ryo; a new threat named Saranbo arrives to claim the armor for himself.
Saranbo gathers forces to prepare to go after Ryo's armor; full of regret and not wanting his friends to get hurt in his defense, a weakened Ryo abandons the team over Mia's objections to face Saranbo alone.
After their friend Marie gets abducted by invaders, Jean and Nadia infiltrate a secret base in the center of the island to try and rescue her; they discover the base's ownership by an organization who call themselves Neo Atlantis.
As earthquakes rattle Industria, its residents fear that another cataclysm will occur; Lepka seeks to revive the massive warplane, Gigant, to make the world his own.