Atragon

During a night magazine photo shoot, a car unexpectedly drives off the road and sinks into the sea. Photographers Susumu and Yoshito witness the crash and are pulled into the mysterious happenings surrounding Makoto Jinguji. The incident sets the stage for a larger confrontation with Mu and Jinguji's return.

The next day, Susumu and Yoshito discuss the earlier incident with a detective and spot Makoto Jinguji, daughter of the deceased Imperial Captain. She is being tailed by a suspicious follower, drawing them deeper into the intrigue surrounding Jinguji. The encounter raises questions about her father's fate and the Mu threat.

Makoto's late father's former superior, Kusumi, is confronted by a peculiar reporter who claims Jinguji is alive and working on a new submarine project. The charge collides with the official narrative and hints at Jinguji's possible return. The confrontation intensifies the mystery surrounding Gotengo.

A mysterious taxi driver tries to abduct Makoto and Kusumi, asserting he is an agent of the drowned Mu Empire. The attempt fails but demonstrates Mu's reach and willingness to act through proxies. The chase ends with the suspect fleeing into the ocean.

A package inscribed 'MU' arrives for Admiral Kusumi. Inside is a film depicting the thriving undersea Mu continent and a demand for surface capitulation. The UN quickly realizes Atragon may be the world’s only line of defense, triggering a push to engage Jinguji.

The United Nations recognizes Atragon as a potential global defense and asks Kusumi to appeal to Jinguji. The appeal aims to rally leadership and unify efforts against Mu. The political groundwork for action begins to coalesce.

Makoto's stalker is arrested and found to be a naval officer under Jinguji. He agrees to guide the expedition to Jinguji’s base but refuses to reveal its exact location. The revelation foreshadows a confrontation with a leader who guards his secrets closely.

After several days of travel, the group arrives at a tropical island inhabited only by Jinguji’s forces. They discover a vast underground dock beneath the island, hinting at the scale of Jinguji’s project. The base becomes the staging ground for the looming conflict with Mu.

Captain Jinguji greets the visitors with a cool demeanor, remaining distant from his daughter and skeptical of Kusumi’s plea. He explains Gotengo was built to restore Japan’s empire and insists it be used for no other purpose. His resolve frames the moral dilemma at the heart of the conflict.

Gotengo undergoes a successful test run, lifting out of the water and flying around the island. The armored submarine demonstrates capabilities far beyond conventional warfare and signals a turning point in the defense of the surface world. The test also raises the stakes for Mu’s plans.

Makoto confronts her father about his reluctance to aid the world, and Susumu reproaches the captain for his selfish stance. The personal rift underscores the broader conflict, and soon the reporters exploit the tension to strike, crippling the base. Jinguji’s resolve hardens as he agrees to pursue a war footing with Kusumi’s support.

The Mu Empire launches a devastating assault on Tokyo and threatens to sacrifice prisoners to the deity Manda if Atragon appears. The threat triggers a decisive mobilization, with Atragon prepared to meet Mu head-on. The world braces for a climactic confrontation between Mu and humanity.

Atragon pursues a Mu submarine to the Mu Empire’s ocean depths, setting the stage for a direct confrontation. Susumu and the other prisoners attempt escape while the Mu forces resist. The battle intensifies as Gotengo and Atragon draw closer to Mu’s power center.

Gotengo engages Manda and employs the absolute zero cannon to freeze the monstrous deity. The creature’s threat is nullified, and Mu’s plans begin to crumble before Gotengo’s assault. The struggle marks a turning point in the siege of Mu.

Gotengo pushes into Mu’s power room, freezing its geothermal machinery and triggering a cataclysmic explosion. The Mu Empire collapses as its heart is silenced. The Mu empress abandons Atragon and swims into the conflagration as the surface witnesses the destruction.