Kei Nagai is a good student whose life turned upside down when he was struck by a truck. After this accident he discovers that he is an immortal (ajin). Feeling shocked and panic, he runs away to an isolated place. Now he can't trust anyone but his childhood friend Kaito.

Tosaki takes the pursuit of government by Ajin. Kei and Kaito are attacked by bandits in search of rewards.

Kaito and Kei are seen and pursued by another motorcyclist. Meanwhile Yu Tosaki recognises Sato, an Ajin hunter at the original accident scene. The other motorcyclist causes the boys to crash, but Kaito recovers and knocks him unconscious.

Izumi fight against a being in Eriko's hospital room. After saying goodbye to Kaito, Kei receives a mysterious invitation.

Kei goes through horrible experiences in a government laboratory and Tanaka encourages you to free his dark side. Sato planning a rescue mission.

Sato starts killing people in the lab. Kei tries to stop him and discovers that Ajin has a weak spot.

With his job at stake, Tozaki takes drastic measures to find out more about Ajin. Sato takes his emphasis on putting into practice a new plan.

Ko flees after Fact reveals his evil plans. Who takes refuge to practice the invocation of his ghost.

Sato prepares to attack. Ko discovers the hideout of Kei and begs for help. Tosaki gets a surprise visit.

Tozaki make new discoveries. Neighbors Mrs. Yamanaka suspect Kei. Sato finalizes his plan.

In the supposed day of the attacks, the scenario of the city is shocking. Sato prepares for action with your team.

With the country all online assisted Tozaki employs a new tactic to deter Sato. Kei loses its disguise.

Mr Keita reports Kei Nagai to the police to claim a reward. Yu Tosaki orders all available forces to the area to catch Kei. When Kei is confronted by the police, he uses his Black Ghost to delay them allowing him to escape into the woods. He uses Ko Nakano’s phone to throw the police off his trail, but Tosaki realizes it's a ruse and closes in.

While running late to attend a party, Shinya Nakamura dies in a motorcycle accident, but revives and learned he is an Ajin.

Four humorous short stories from the points of view of Sato and Tanaka (2 stories), Izumi and Tosaki (1 story), and Ko and Kei (1 story).

Satō emerges from the rubble as he blew up an existing tunnel below to escape being crushed by Nagai's plan. Satō begins to hunt Nagai and the others as they attempt one last attempt as stopping him before the military unleashes a gas attack.

Kei and Ko train their bodies and begin to develop strategies to fight Tosaki. Kei spends time talking about his IBM with Ogura, realizing Kei's ghost is an extreme abnormality. While they begin to strategize, Sato makes his next move taking down a plane with his second target.

Sato is able to assassinate another off of the list. Nagai and Tosaki begin planning their counterattack against Sato. Nagai begins to struggle with the behavior of his IBM, wondering if he himself has to change. Tosaki also let's Nagai know Kaito's current condition.

Kaito is in prison after helping Kei escape. He encounters prisoners ganging up on another prisoner after a successful escape attempt. The prisoner wants no help from Kaito. It begins to be clear the prisoner is hiding something.

Kei continues his training. Tosaki attempts to get the Minitser's schedule. The Minister refuses, which leads Tosaki to attempt to steal it. However, the American investigators interfere.

Tosaki has been captured. Izumi rushes back to the hideout and insists they rescue him. Initially refusing, Nagai ultimately leads a team to rescue Tosaki from the Americans.

Nagai and the group pursue the Americans and Tosaki. Izumi manages to catch up with them and ultimately rescue Tosaki. Unfortunately, this means they missed their window to catch Sato.

Tosaki manages to get his team allowed into the building where Sato's next target is. Just as the clock ticks closer, a truck rushes in and sets off an E.M.P. bomb, rendering all electronics and new anti-Ajin guns useless. Sato charges in for an old fashioned gun fight.

Nagai and the group return after being defeated by Sato. Nagai struggles to deal with his failures. Sato continues towards his third and final wave, an Ajin run Japan. Tosaki tries to mobilize everyone once more to stop Sato, but Nagai refuses.

Ajin are humans that cannot die. Seventeen years ago, they first appeared on a battlefield in Africa. From then on, more of their kind are discovered within the human society. Their rarity in appearance means that, for experimental purposes, the government will generously reward anyone who captures one. In the present day, for what a certain high school student expects to be a typical summer holiday, his life is about to turn unexpected...

Unrest begins as Satō-san releases a chemical weapon onto the population. People begin trying to attack the families of Ajin. Nagai saves his sister with the assistance of Kaito. Nagai entrusts his sister into Kaito's care.

People from Satō's group desert and make contact with Nagai. The US plans on releasing the chemical weapons on Satō in the sewers. Tosaki is called and asked for assistance, which leads Nagai and the group to go after Satō once more.

Although he was caught off his guard, Sato has one last plan: to kill the rest of the team.

Taking place immediately after the prologue scene from Episode 1, Satou's background is explored.