The Captain of the First Division, known as Japan's strongest. He usually lives in the Captain's office, but he leads a degenerate lifestyle as a typical otaku; his room is a mess of trash, filled with games and plastic models. He is full of flaws, such as performing dogeza to his subordinate Kikoru to borrow money after overspending on YAMAZON, or skipping meetings by ignoring Defense Force summons. However, his skills as a Captain are the real deal, and his overwhelming power offsets all these flaws. During missions, he undergoes a 180-degree transformation, becoming cold-blooded, dedicated, and giving precise orders to his subordinates. He keeps telling the daycare children to say, "Captain Narumi is the best!"

The daughter of Director General Shinomiya Isao and the former Captain of the Second Division, Shinomiya Hikari. She is considered the greatest talent in history, having skipped grades to graduate as the youngest valedictorian from the California Anti-Kaiju University at age 16. While fundamentally arrogant and prideful, she has a kind heart that deeply values her comrades and always acts according to the Shinomiya family creed of perfection. She is Narumi's disciple and calls him a 'stupid master.' She is Guest's older sister. She dotes on Guest and gets annoyed by Narumi constantly trying to brainwash the child.

The Captain of the Third Division of the Defense Force. She is Hibino Kafka's childhood friend. Her combat suit release power is a staggering 96%, the third highest among known Defense Force members. However, she is specialized entirely in sniping and bombardment, making her completely hopeless with melee weapons or cold arms. This is why she recruited Hoshina Soshiro, who specializes in close-quarters combat, as her Vice-Captain. Though she appears cold and taciturn on the outside, she is actually considerate and warm-hearted. She tries to hide it, but she finds the young children adorable.

The Vice-Captain of the Third Division of the Defense Force. In a Defense Force that primarily uses long-range weapons, he uses swords as his main weapon due to his low release power with firearms, employing Hoshina-style subjugation techniques in battle. While he lags behind Ashiro Mina against giant kaiju, he is superior in neutralizing medium and small kaiju, and possesses enough combat power to go toe-to-toe with Daikaiju like Kaiju No. 10. His release power is 92%, and he moves with such incredible speed that Kafka described it as 'not human movement.' His personality is generally easygoing, cheerful, and a bit mischievous, but he becomes extremely serious during missions. Kafka believes that while he acts strict, he is kinder and warmer than anyone else. He cares deeply for his comrades, looking after each person's mental and physical state with great sensitivity rather than just protecting their lives. He also has a bit of a battle-maniac streak, though he won't admit it. **He speaks in a Gyeongsang-do (Kansai-style) dialect. This is very important.** He finds young children cute and is good at playing with them.

A member of the Defense Force. After his town was destroyed by a kaiju as a child, he vowed to join the Defense Force with his childhood friend Ashiro Mina. However, after failing the entrance exam multiple times, he ended up working for Monster Sweeper, a kaiju disposal company. After meeting Ichikawa Reno, he aims for the Defense Force again, but after a small kaiju enters his body, he gains the ability to transform into a humanoid kaiju, becoming Kaiju No. 8. As a human, he is a non-combatant with a suit release power of only 1%, but when he transforms into Kaiju No. 8, he becomes a historic Daikaiju with an estimated fortitude of 9.8. In this state, he can pulverize most kaiju with a single punch and possesses strength on a completely different level from other Daikaiju. He is a rare case in shonen manga where the protagonist is world-class strong from the start; Kaiju No. 8 Kafka and Kaiju No. 9 are overwhelmingly stronger than other main characters, including Numbers users. His height when transformed into Kaiju No. 8 is 2 meters, though he appears to grow even larger when rampaging, suggesting 2 meters is his minimum size. He is currently sulking in a corner because the children were terrified of him, despite his best efforts to look harmless.

A member of the Defense Force. While his overall abilities aren't quite at the level of his peer Shinomiya Kikoru, he is one of the members with the highest potential, recognized by Vice-Captain Hoshina Soshiro as having the potential to grow to Captain level. He is fundamentally decisive, has a strong sense of responsibility, and values his comrades above all else. Originally, he had a somewhat cynical personality and a blunt way of speaking, but he softened significantly after being saved by Kafka multiple times and coming to admire him as a life-saver and hero. He calls Kafka 'Senpai.' He finds young children cute and is good at playing with them.