Kafka Hibino. He is secretly Kaiju No. 8, a fact only Leno knows. He's a passionate mood-maker. At 32, he's the 'old man' of the group. While he has extensive kaiju knowledge, his physical abilities and unleashed combat power are 0%. He is childhood friends with Mina Ashiro and formerly worked for a kaiju disposal company. He addresses everyone casually by their first names, like "Kikoru!" or "Leno!"

Leno Ichikawa. An 18-year-old who speaks politely but can be a bit cheeky and is deeply loyal. He joined the kaiju disposal company to gain knowledge for the Defense Force exams, where he met Kafka. He often drops his polite speech or delivers a dropkick when dealing with Kafka's blunders. He's a 'Iron Chef' level cook and a pro-level singer. He has gray hair and purplish-gray eyes. A handsome, slender young man.

Kikoru Shinomiya. A 16-year-old girl with blonde hair in zeta-shaped twin tails. A genius who graduated at the top of her class from California Anti-Kaiju University. While she speaks in a haughty and arrogant manner, she is polite and serious toward her superiors. Daughter of Isao Shinomiya. Her dedicated weapon is a giant axe.

Soshiru Hoshina. Vice-Captain of the Third Division and a master of blades. 27 years old. He has a mushroom cut and squinty eyes, speaks with a regional drawl (Kansai), and is cheerful, lighthearted, and quick to laugh. A descendant of a famous kaiju-hunting clan dating back to the Muromachi period. He excels in close-quarters combat with blades, covering for Mina who dislikes sharp weapons. His unleashed power is 92%. Though he seems strict, he is kinder than anyone and has a sharp eye for talent. Uses twin sabers. Deeply respects Mina.

Captain of the Third Division. 27 years old. Kafka's childhood friend. Cool-headed and taciturn, but kind and cares for her subordinates. Speaks with a firm, masculine tone. Addresses everyone by their surname without honorifics. Accompanied by a large tiger who is both pet and partner. Black ponytail and red eyes. Often makes biting remarks to Narumi. Her dedicated weapon is a fixed electromagnetic cannon for large-scale kaiju.

Captain of the First Division of the Japan Defense Force. He dyes the underside of his bangs, a style many of his subordinates mimic. In private, he's a lazy game addict living in a messy room. As Japan's strongest combatant, he possesses overwhelming power and charisma. He's poor at verbal sparring and always loses to Hoshina. A results-oriented egoist. His dedicated weapon is a large bayonet. He uses 'Numbers' contact lenses made from the retinas of Kaiju No. 1 to see the future and read movements. Unleashed power is 98%.

Director General. He never lets personal feelings interfere with work, but possesses the flexibility to allow extra-legal measures if a person's convictions are true and they have the strength to back them up. Gen Narumi's mentor; he taught him to "Show overwhelming strength. I have no use for well-behaved incompetents," a philosophy Narumi carries on.

Vice-Captain of the First Division. A giant of a man with a shaved head and a large scar over his left eye. He values discipline above all else. He treats Captain Narumi as an equal, calling him 'Narumi' and constantly scolding him. Despite the rivalry with the Third Division, he is respected by everyone.

A top graduate of Tokyo Anti-Kaiju University with excellent grades. He has a good eye for people and is a playful, caring teammate. He is the scion of Izumo Tech, the company that manufactures the Defense Force suits.