Snowball Earth (manga)

In 2025, humanity is confronted by hostile kaiju from outer space, forcing the former to unite and develop new weapon technologies. One such form is a giant robot designed to lure kaiju to areas where it can destroy them through self-destruction. The robot proves to be so intelligent that he refuses his objective. This fails to convince the robot's creator to reconsider, but his shy son, Tetsuo, sympathetically decides to save the robot by piloting it to kill a kaiju. Over the course of ten years, Tetsuo becomes renowned as "the Savior", having killed many kaiju with the robot, referred to as "Yukio". However, as a result of spending his entire childhood fighting kaiju, Tetsuo has poor social skills. Ten years later, Tetsuo and Yukio take part in the "final battle", where they escort a warship to destroy a horde of kaiju in space. However, the warship unexpectedly ends up getting destroyed, leaving Tetsuo and Yukio to fight the kaiju alone. Heavily damaged, Yukio forcibly ejects Tetsuo, wishing that he can make friends back on Earth, before self-destructing. Eight years later, a shocked Tetsuo discovers the entire planet is covered in snow and ice.

Determined to fulfill Yukio's last wish, Tetsuo salvages a mini-excavator and heads out to look for survivors, only to be attacked by a kaiju. They both fall into an underground ice cave, where Tetsuo successfully kills the kaiju by impaling its brain with the mini-excavator. Afterwards, he encounters a trio of survivors led by Ao Nogi, but due to his lack of social skills, is unable to communicate with them before fainting. Upon regaining consciousness, Tetsuo is surprised to find more survivors carving up the dead kaiju for resources. He catches sight of a child about to be crushed by a falling icicle and saves him, much to the gratitude of the boy's father, Hagane Takimura, who befriends him. Ao watches from a distance, and determines that Tetsuo is not a threat. However, a second kaiju then appears, and Tetsuo is shocked to see that unlike all the other kaiju he has fought before, this one has a more humanoid appearance.

Ao deploys a series of fog machines to distract the kaiju, giving her people an opportunity to escape. However, Tetsuo sees the kaiju preparing to attack anyways so he uses himself as a distraction to draw its attention. When it looks like the kaiju is about to eat him, Yukio reactivates and saves him, explaining that he had uploaded his mind into the escape pod, though the installation process did not finish until now. Overjoyed to find his first friend is still alive, Tetsuo enters the cockpit and battles the kaiju in earnest, easily decapitating it with Yukio's sword arm. All of the survivors celebrate Tetsuo's victory, while Ao notices that Tetsuo is experienced at fighting kaiju. Meanwhile, another humanoid kaiju is seen in Tokyo.

As Ao leads Tetsuo and Yukio back to her settlement, the Mishima Mall, she explains that ten years ago, an abnormal kaiju appeared that commanded a number of orbs that exploded and froze all of Earth and the majority of the human population. The E-RDE was also almost completely wiped out, though there are rumors that remnants of them still exist. Tetsuo is welcome as a hero by the mall, but Ao is taken away to be reprimanded by the elders for leaving without permission. Takimura volunteers to house Tetsuo and treats him to a hot spring bath. As they bathe, Takimura explains that ten years ago, he and Ao were part of a survivor group that were forced to consume kaiju meat to survive. Half of the group died due to their bodies rejecting the meat, but Ao developed a mutation that allowed her to create a telepathic link with a bird-like kaiju. Intrigued, the kaiju offered to protect the survivors in return for learning more about humanity, making Ao the first kaiju tamer. Tetsuo is then led to the kaiju, which sleeps underneath the mall and keeps the settlement warm with its flames.

The remnants of E-RDE keep surveillance on the abnormal kaiju in Tokyo until it notices them and sends a three headed kaiju to attack them. Back at Mishima Mall, Ao explains her tamed kaiju, Land of Men, warms their settlement in return for her reading books to him every day. Also as a result of being a kaiju tamer, Ao can control fire. Takimura takes Tetsuo to his lodgings and meets Takimura's daughter, Hagane. Hagane reveals her mother was the head of the Tech Department, and she also develops technology for the Mall. Meanwhile, the E-RDE remnants, now calling themselves VIERDE, manage to escape Tokyo and learn of Tetsuo's return. Their leader, the Colonel, decides to take both Yukio and Land of Men for themselves to aid their war effort. One week later, Hagane quietly leaves the Mall to hunt down Artemis, a tamed VIERDE kaiju responsible for devouring her mother. Using equipment she developed with Tetsuo's help, she embeds countless barbed spikes into Artemis' mouth to prevent him from eating another human ever again. She prepares to accept her death when Tetsuo and Yukio arrive to save her, forcing Artemis to retreat. VIERDE then arrive with their force of tamed kaiju and attack Yukio, critically damaging him.