Jamie is a marketing executive turned delivery driver who accepts a job lifting and hauling for an animal rights organization in alternate-Earth Greenland. Having written a master's thesis on futuristic literature, Jamie possesses an affinity for science fiction that proves highly useful in their new environment. Jamie starts with little confidence but holds strong personal morals and a desire to help others.

Aparna is an Indian American biologist from Los Angeles who joins Tanaka Base's Gold Team following a breakup. She initially approaches the assignment primarily for the financial compensation but quickly develops a fierce dedication to studying the massive creatures. She applies strict scientific principles to understand complex biology in an alien ecosystem.

Kahurangi is a Māori organic chemist and geologist from New Zealand working on the Gold Team. He formulates and tests chemical agents to influence creature behavior safely in the field. He uses humor as a coping mechanism in the highly dangerous environment of Kaiju Earth.

Niamh is a nonbinary Irish astrophysicist who studies dimensional barriers and environmental anomalies for the Gold Team. They possess a strict adherence to established scientific practice and vocalize their concerns directly. Niamh acts as a fiercely loyal protector of their colleagues and the natural world.

Rob is the opportunistic CEO of the food delivery company füdmüd and a representative of the defense contracting firm Tensorial. He comes from a wealthy family with a history of military contracting and nuclear energy interests. He views the natural world strictly in terms of financial and political capital.

Martin Satie is a French Canadian colonel in the Royal Canadian Air Force who serves as a liaison and pilot for the Kaiju Preservation Society. He genuinely enjoys the stimulating fieldwork of his assignments and maintains a strict moral code regarding his duties.

Tom is a former business student who works for the Kaiju Preservation Society. He actively recruits new members to the organization and serves as a guide for the recent arrivals. He introduces the new scientists and workers to the harsh realities of their environment and explains the history of the organization.

Brynn leads the Tanaka Base Gold Team. She oversees the daily operations, scientific research, and field missions on the base, maintaining strict rules to ensure the safety of both the human crew and the local ecosystem.

Bella is a massive, highly endangered female kaiju who functions as a walking ecosystem powered by a biological nuclear reactor. She becomes the central focus of Tanaka Base's research when she establishes a nest near a vulnerable dimensional barrier.

Edward is an endangered male kaiju and the only other known member of Bella's species. He possesses a biological nuclear reactor and requires chemical intervention from the human science team to successfully mate.

Riddu is a specialized trainer responsible for teaching new members how to survive encounters with hostile fauna. She takes a highly practical, often blunt approach to instruction to ensure recruits understand visceral danger.

Ion is a biologist on the Blue Team at Tanaka Base. He participates in field missions to set up data-collection instruments near massive biological hazards.

Tipton is a US military official who visits to assess the risks following a recent nuclear venting incident. He represents the American government's interests and security concerns regarding dimensional boundaries.

Qanisha is Jamie's former coworker at the food delivery company füdmüd. She makes a wager about employee retention that directly leads to Jamie's sudden demotion to delivery driver.

Brent is Jamie's roommate in New York City during the early months of the COVID-19 pandemic. He offers emotional and logistical support when Jamie faces sudden employment changes.

Laertes is Brent's boyfriend, a trans man whose conservative parents present a housing complication during the pandemic.

Gracia conducts the intake and interview process for the Kaiju Preservation Society. She evaluates candidates for their physical fitness, discretion, and ability to handle highly unusual scenarios.

Sylvia is Jamie's predecessor on the Red Team. Before returning to her life on main Earth, she leaves behind a potted plant and a welcoming letter to help the next occupant adjust to base life.

Dave is a soldier working at a remote encampment on main Earth. He acts as perimeter security without full context of the operation he guards.