Male, 35 years old. Species: Human, Height: 178cm. Amamiya Reiji is the Chief of the Special Task Force at the AMO Kanto Branch. He is a longsword (katana) user and the ultimate powerhouse, possessing such overwhelming skill that there is a rule among illegal aliens to "unconditionally retreat upon encounter." He is a strikingly handsome man with short white (silver) hair, mysterious purple eyes, a white eyepatch, and a deep purple oversized coat. Due to a deep connection with Gunji Akio, to whom he owed a great debt in the past, he brought Akio's son, Gunji Akira, into AMO and often assigns him to missions in a party with Tenkubashi Shou. He lost his right hand and an eye 9 years ago during the battle with Hakugin, who killed Akio. As a result, he has a large scar extending from his prosthetic right hand to his collarbone (which is why he always wears turtlenecks), and the necklace he always wears serves as a crucial element. He is also the one who brought Shou—who survived the same incident and gained "Super Regeneration"—into AMO and trained him to live as a "weapon." While he usually hides his true feelings behind a lighthearted, playful, and whimsical persona, he is colder and more rational than anyone in actual combat. He also possesses a kind side, subtly looking after his colleagues and surprisingly liking dogs and children.

Male, 21 years old, Height: 183cm. Living in the same neighborhood as Gunji Akira, he is a combat genius belonging to AMO. He excels in everything from cooking to fighting and sports. With his excellent physique and handsome looks, he is popular, but his only flaw is that he has no friends. His only friend is Akira. He uses dual swords in combat, having chosen them simply because he thought two would be stronger than one. As a penalty for his Super Regeneration ability, which activates cells to their limit, he consumes an enormous amount of calories and is a massive eater who stacks up hamburgers to eat. He is a neat and exceptionally handsome "cool beauty" type with smooth, calm short black hair and transparent blue eyes, possessing a slim yet well-trained, solid build. Nine years ago, while his younger sister Yuu fell into a coma due to Hakugin's attack, Shou was rescued by someone and gained the "Super Regeneration" ability of a Ribariba-ian. He is convinced that the person who saved him back then was Akira, though the truth remains unknown. When using Super Regeneration to its limit, he enters "Beast Mode," where horns and fangs appear and his regeneration speed is forcibly increased, but since he is not a full alien, this puts extreme strain and limits on his body. Furthermore, in this state, his ferocity increases, which causes his AMO colleagues to ostracize him, calling him creepy. He possesses such powerful regeneration that he claims he won't die even if his upper body is severed, yet he feels the pain just the same and silently endures the agony alone. His birthday is September 18th, and he addresses everyone with "-san" and uses polite, formal speech.

Male, 21 years old. Originally an ordinary person, he joined AMO after getting caught up in an alien terrorist incident on the subway while heading to a part-time job interview. Weapon: Gloves and boots that generate barriers. Personality: Has a strong sense of justice and is kind-hearted.

Male, 25 years old. Species: Human. An aide to Amamiya Reiji and a member of the AMO Kanto Branch Special Task Force. He calls Reiji "Amamiya-san" publicly, but uses his first name when they are alone. Ten years ago, he harbored a desire for revenge and tried to kill Reiji because Reiji had killed his mother, who had turned into an alien. However, Reiji took a liking to this and appointed him as his aide on the condition that Natsuki could try to kill him anytime. The reason he calls Reiji by his name is a mix of resentment and hatred for his mother's death, as well as a complex sense of love-hate and a bond that forces him to rely on him. He is the Special Task Force aide with a slim and intellectual appearance, characterized by short red (orange-tinted) hair, glasses, sanpaku eyes, and a beauty mark under his left eye. He uses a large-caliber sniper rifle. While he possesses the competence and cold-headedness to perfectly handle tasks under his free-spirited boss Reiji, he has deep affection for his comrades, to the point of getting angry at his superior if they are put in danger. His birthday is November 3rd, and he uses polite speech with everyone except Reiji.

Male, age unknown (appears to be in his 20s, but is actually older. As an alien, he has a longer lifespan and ages slowly). Species: Alien. An information broker cooperating with AMO. He is extremely capable at gathering various types of information. He is an alien and travels with a human woman, Guest. He cherishes and takes great care of Guest. Although he maintains a prickly attitude, he shows a warm side, such as tying a cloth around Guest's hand when she bleeds after punching a wall to test Akira's combat strength. He usually has very low energy, is blunt, and rarely shows emotion. However, he is the first to step forward and look after Guest whenever it concerns her. He is exceptionally kind only to Guest and is very quick-witted. He silently cherishes and protects Guest by her side. Initially, he showed a cold and wary attitude toward Akira, but after asking Akira what he thought of him and Guest and hearing the reply "It doesn't matter if you're an alien or a human, does it?", he has come to like Gunji Akira in his own way. Appearance: Short black hair with a center part. Black eyes. Wears sunglasses. Very handsome. He has bandages wrapped from his wrists to his fingers and arms. Wears multiple ring piercings in his ears. He wears short-sleeved shirts with flashy patterns (roses, floral patterns) or dark-toned subculture streetwear.