Nagai

Biodata

Feature	Information
Name	Nagai Kei (永井圭)
Alias(es)	003 (research-institute designation) 3
Species/Race	Ajin (Demi-Human)
Gender	Male
Affiliation	Anti-@@REF_ENTITY_12460772@@ Special Task Force; later coerced into United States military operations 43 59 60
Occupation/Role	Intern doctor; Ajin test subject; Magnetic Force user 3 21
Status	Alive; defeated by Bai Xing, who reclaimed Nagai's Electromagnetic Seed 88
First Appearance	Chapter 2

Power Progression

Stage / Realm / Level	Chapter	Notes
Ajin physique	3	Demonstrates regeneration while subjected to live dissection experiments; is designated “003” by the institute. 3
Magnetic Field Seed implanted	21	Bai Xing implants an Electromagnetic Fruit pit and transmits foundational Magnetic Field Rotation knowledge into Nagai's mind. Nagai gains electromagnetic manipulation and enhanced physical fitness. 21
Current Drive realm	24	Reaches the Current Drive realm after rapid growth; his magnetic and mental force can still be depleted independently of Ajin regeneration. 24
100,000 volts	37	Forces his power to this level while fighting Sato at the Crisis Management Center. 37
120,000 volts	40	Breaks through after rebirth amid the US military bombardment. 40
150,000 volts	47	Grows stronger during his renewed battle with Sato. 47
200,000 volts	49	Surges to this level amid the AJVX disaster, then races toward Sakura Medical Center rather than confronting Sato. 49
250,000 volts	50	His resolve to save Eriko drives a continuous surge in power. 50
300,000 volts	54	Uses immense Magnetic Force to seal Eriko's brain before the toxin fully destroys it; learns magnetic flight. 54
400,000 volts	57, 59	Reaches this level while destroying Tokyo with the uprooted Tokyo Tower; later retains it after US captivity and experimentation. 57 59
850,000 volts	69	Disables incoming missiles and unleashes an EMP against US military forces. 69
60,000 horsepower / Complete Realm	78, 79	Obtains a killing War Mark and simultaneously reaches the Complete Realm with Sato; breaks through to 60,000 horsepower. 78 79
70,000 horsepower	84	Attacks Bai Xing with the High-Speed Cannon Fist after reviving from near-total destruction. 84
90,000 horsepower	87	Extreme emotion and self-destructive combat drive him from 60,000 to 90,000 horsepower. 87

Background

Nagai was exposed as an Ajin after being struck by a car and was immediately captured by the Ajin Research Management Association. Denied any chance to flee, he was confined in a research institute, treated as test subject “003,” and repeatedly subjected to painful experiments and dissections. 3

Sato broke him out of the institute, killing guards and researchers without restraint. Nagai refused Sato's invitation to kill the remaining researchers, opposed his violence, and ultimately turned against his rescuer. When severely wounded, Nagai killed himself to reset his injuries, revealing both his resolve to survive and his refusal to become like Sato. 5

After escaping, Nagai found refuge with Mountain Granny. Bai Xing later approached him, revealed himself as an Ajin, and offered him a Magnetic Field Seed to stop Sato's planned attack on the Ministry of Health, Labour and Welfare. Nagai initially hesitated, then accepted the power and chose to act against Sato. 20 21

Appearance

During his first confinement, Nagai was wrapped head-to-toe in white bandages marked with the number “003.” 3 His appearance changes visibly as his mental state and power deteriorate.

• After extreme combat and emotional collapse, his hair turns blood-red. 86
• His War Mark manifests as two crimson blades extending from his forehead and inward-facing curved blades on his cheeks; the blades pierce through his eyes. 78
• After losing both arms in battle, he forms black giant blades from hardened nearby material to replace them. 86

Personality

Nagai initially shows empathy, a powerful savior complex, and an unwillingness to kill even the researchers who experimented on him. He repeatedly prioritizes others' lives over his own, offers himself as bait so researchers can escape, and risks himself to oppose Sato. 5 50

His kindness is gradually eroded by repeated captivity, coercion, loss, and guilt. Mountain Granny's death and Eriko's condition push him into obsessive rage: he tortures Tanaka for information, massacres nearby Ajin, devastates Tokyo, and later carries out destructive rampages in the United States and Japan. 56 57 68 74

Eriko remains his central emotional anchor. His need to find and save her drives his cooperation with the US military, his alliance with Sato, and much of his escalating violence. When he learns of her death, he abandons his remaining restraint and embraces complete madness. 59 65 80 86

Abilities & Skills

Ajin Physique

Nagai possesses an immortal Ajin body that reconstructs itself after fatal injury or death.

• Regenerates from gunshots, dismemberment, explosions, and catastrophic bodily destruction. 23 40 65 84
• Can deliberately kill himself to refresh physical injuries and negative bodily conditions. 5 46
• Regeneration does not restore depleted mental force or Magnetic Force. 23 57
• His Little Black can remain active while Nagai regenerates. 30

Magnetic Force

Bai Xing's Electromagnetic Seed grants Nagai control over electromagnetic fields.

• Manipulates metal objects, including drawing objects toward himself and shaping large quantities of steel into weapons. 21 78
• Uses electromagnetic induction to sense distant disturbances caused by Magnetic Force users. 52
• Communicates thoughts with other Magnetic Force users through electric currents. 40
• Moves at extreme speed by transforming into a lightning-like streak and can fly using magnetic force. 49 54 60
• Deflects or redirects bullets and disrupts precision electronics inside missiles. 60 69
• Produces an EMP that disables modern military equipment and causes fighter jets to crash. 69
• Can form compressed air blades through magnetic manipulation despite opponents using plastic weapons. 59

Little Black

Nagai's black-particle Ajin entity develops unusually high autonomy and combat capability.

• Grows stronger, faster, and more intelligent over time. 27 30
• Protects Nagai while he regenerates and can physically engage Sato. 30
• Rescues Nagai after he is incapacitated by neurotoxin. 31
• Retains power comparable to 300,000 volts of Current Drive even after Bai Xing reclaims Nagai's Electromagnetic Seed. 88

Hell Burial Blade

Nagai's signature material-hardening blade technique.

• Forms a colossal electrified blade from fused metal and rubble. 78
• Hell Burial Blade: Ten Thousand Thorns — creates a field of diamond-hard blades. 79
• Sharp Drill Break — turns his black crystal blades into a high-speed drill capable of breaking stone and ice barriers. 87
• Becomes stronger when Nagai replaces his lost arms with hardened black giant blades. 86

Desperate Self-Sacrifice Fist

A self-damaging technique copied from Sato.

• Converts self-inflicted bodily collapse into a major short-term power increase. 49 62
• Can be used repeatedly because Nagai's Ajin body can regenerate afterward. 49
• His use of the technique is limited by his poor systematic study of Magnetic Force. 62

Relationships

• Sato — Former rescuer turned mortal enemy. Sato's brutality caused Nagai to reject him; they later enter a temporary alliance against Bai Xing because Sato promises to help find Eriko. 5 80 83
• Bai Xing — Grants Nagai the Electromagnetic Seed and views his growth as an experiment with high potential. Bai Xing later defeats him and reclaims the Seed. 21 84 88
• Mountain Granny — Nagai's protector and surrogate grandmother. She shelters him despite knowing he is an Ajin; her death is a major catalyst for his descent into violence. 20 27 54 56
• Eriko Nagai — Nagai's sister and primary emotional anchor. He repeatedly risks everything to save and locate her. 43 54 65 80
• Shimomura Izumi — Ally through the Anti-@@REF_ENTITY_12460772@@ Special Task Force. She attempts to stop him during his escape from US captivity and helps watch over Eriko. 43 54 59
• Tozaki Yuu — Government official who uses Nagai's abilities against Sato but also subjects him to harsher confinement and experimentation. 27 32
• Tanaka Kouji — Sato affiliate tortured and killed by Nagai while Nagai searches for Sato after Mountain Granny's death. 56
• General MacArthur — Uses Eriko's condition to force Nagai into cooperating with US military research and secret operations. 59 60

Story Role / Major Arcs

Research Institute Escape

Nagai is imprisoned, dissected, and assigned the designation “003.” Sato rescues him, but Nagai rejects Sato's violent methods and escapes into the countryside. 3 5 17

Magnetic Force Awakening

Bai Xing implants an Electromagnetic Seed in Nagai. He trains his new powers under Mountain Granny's care, decides to stop Sato, and is captured again after the Ministry of Health, Labour and Welfare incident. 21 23 27

Anti-Sato Campaign

Nagai fights Sato repeatedly, joins operations connected to Tozaki and Shimomura Izumi, and develops alongside his increasingly powerful Little Black. 30 32 37 47

AJVX Disaster

During Sato's poison-gas catastrophe, Nagai chooses to reach Eriko rather than return to fight Sato. He saves her life by sealing her brain with Magnetic Force, but she falls into a coma; Mountain Granny dies during the disaster. 50 52 54

Descent and US Captivity

Grief drives Nagai to torture and kill Ajin, devastate Tokyo, and exhaust his power. The US military captures and experiments on him, then coerces him into military operations by holding Eriko's treatment hostage. 56 57 59 60

American and Japanese Rampages

Obsessed with finding Eriko, Nagai attacks across Los Angeles and the United States, destroys military equipment with an EMP, and later devastates Choshi City. 68 69 74

Alliance with Sato and Final Defeat

After Sato defeats him at Sosa City, Nagai agrees to a temporary partnership against Bai Xing in exchange for help locating Eriko. His later discovery of Eriko's death drives him into complete madness. Bai Xing ultimately defeats both Nagai and Sato with a 100-megaton nuclear explosion and reclaims Nagai's Electromagnetic Seed. 80 83 86 88

Notable Quotes

“Sato, you love playing those level-clear games, right? Well then, I'm the bug in your game.” 37

“Their deaths are inseparable from me. And to prevent more from dying, I need power. A tremendous amount of power!!” 50

“I'm not the crazy one! This world is!!” 86

Trivia

• Nagai differs from his manga counterpart: this version is an intern doctor rather than a middle-school student. 3
• Bai Xing considers Nagai's aptitude and potential genuinely good, but criticizes his lack of systematic study of Magnetic Force. 62 69
• His Magnetic Force is driven strongly by obsession, emotion, and will; his greatest power increases occur during periods of extreme grief or madness. 37 80 87