Atragon (1963)

In a world shrouded with mysterious happenings, two engineers inexplicably vanish, setting off a ripple of unease across the globe. The enigmatic former admiral Kosumi, his secretary, and cherished goddaughter Makoto Jinguji, narrowly escape a kidnap attempt thanks to the swift intervention of photographer Susumu Hatanaka and his aide, Yoshito Nishibe. The veil of mystery lifts to reveal the ancient Mu Empire, a civilization lost to time 12,000 years ago, weaving the strings of chaos. The Muans, with expansionist ambitions, are set to reclaim the surface world they deem their lost colonies. The drama deepens as Captain Jinguji, Makoto's estranged father, suffers the theft of his I-403 submarine and the blueprints for the colossal submarine, Atragon, by the cunning Muans. As the Muan assaults escalate, the world looks to the reluctant Jinguji for salvation, with even his daughter Makoto adding her heartfelt plea. Still nursing the bitterness of Japan's defeat in World War II, Jinguji stubbornly refuses. However, the battle becomes personal when Makoto and her newfound love, Susumu, are seized by the Muans. Facing the mighty Muan Empire and their towering serpentine beast Manda, Jinguji is forced to confront his past and wield his ultimate weapon. The stage is set for a high-stakes game, where the fate of the world hangs in the balance, in this thrilling saga of ancient empires and modern courage.

Atragon is an action movie featuring Tadao Takashima and directed by Ishirō Honda.

Atragon is currently streaming for free (ad-supported) on Filmzie, Plex, Plex Player, The Roku Channel, Tubi TV and VUDU Free and it's also available on Criterion Channel.

It is also possible to buy Atragon on Amazon Video and Vudu.