Introduction arc

The Introduction arc is the first story arc of the Fire Force manga series. It follows Shinra Kusakabe and Arthur Boyle's enlistment in the Special Fire Force Company 8, the Rookie Fire Soldier Games and the parole of Setsuo Miyamoto. This arc takes place in chapters 0-12 in the manga and episodes 1-4 in the anime.

Shinra Joins the Force
On a train, a human is set ablaze. Meanwhile, Shinra makes his way towards the train station, where he bumps into a girl and scares her away with his grin. Upon arriving to the station, an alarm goes off, which announces that the train was caught in flames, after which, people begin evacuating the premises as a Flame Human crawls from inside the train carriage. Before Shinra could take action, the Special Fire Force Company 8 arrives. The brigade confronts the being, eventually managing to destroy its core. After the ordeal, Shinra notices a falling light and uses his Ignition Ability to save Iris underneath, and later introduces himself as the team's newest recruit. When the brigade returns to the headquarters, Shinra is introduced to Takehisa Hinawa and Akitaru Ōbi. When asked why he joined the brigade, Shinra replies that he wishes to become a hero. After the girls have a shower, Shinra is introduced to Maki Oze and Iris. The brigade members soon begin talking about the Human Body Ignition Phenomenon and that their mission is to unravel the secrets surrounding it. In bed, Shinra recalls the death of his family. Straight after, the team is notified that a fire has broken out, which forces to them to depart to the scene.

Shinra's First Mission
Shinra goes on his first mission with the brigade. After arriving at the scene, Akitaru warns the crew of the falling debris in the factory, in which the fire is taking place. Heading into the building, Shinra contemplates the act of destroying a Flame Human and how it is equivalent to killing a real person. Shortly after heading in, the brigade comes across the burnt corpse of the last employee of the factory, whom they set out to save, who failed to escape, making their primary mission to extinguishing the threat. At the scene, Akitaru reminds Shinra the purpose of the blue lines. Distracted by Maki showing her Second Generation abilities, Shinra is caught off guard by the Flame Human, who knocks him unconscious, causing him to recall his past, before being woken up and told to stand up. Shinra finally decides to fight. With the squad cooperating in order to deal with the intelligent Flame Human, Shinra launches himself towards the enemy, igniting his feet in the process. The boy delivers a kick to the core of the Flame Human's heart, sending her to the afterlife in peace. He overhears the spectators chanting for him while the rest of the crew praises him, saying that he has finally become the hero he longed to be. Elated, Shinra shows off a delighted smile.

Arthur Joins the Force
Akitaru informs Shinra that a battle tournament will be held between the newcomers of all Special Fire Brigades. Arthur Boyle arrives at the headquarters and bumps into Shinra. On the roof, Maki shows Iris how she can create a fireball creature, but their conversation is cut short when a fight breaks out between Arthur and Shinra. The former unsheathes his bladeless sword and introduces himself to the girls as the "Knight King". Takehisa arrives, stops the bickering between the two Fire Soldiers and orders Maki to fight them. With her abilities, Maki disposes of Shinra with ease and attempts to extinguish Arthur's Excalibur, but to no avail. Using her hand-to-hand combat skills, she makes Arthur kneel before her, kicking him in the face with her knee, causing the boy to insult Maki, which forces her to create a huge flame creature. After the battle, Shinra is baffled and thinks to himself that he needs to become stronger. In the meantime, Takehisa extinguishes Maki's creature, much to her horror, and Akitaru ponders about how long will it take for Arthur to arrive.

Arthur's First Mission
Shinra, Arthur and Akitaru eat at Ippudo Ramen, where the three strengthen their friendship. Back at the base, Takehisa gives Shinra a battleaxe, and offers Arthur one, but he refuses to accept it. Akitaru then complains about the maintenance and wishes that the brigade had a stoker in their ranks. In the meantime, Mikako returns home only to see that her father has turned into a Flame Human. The brigade moves out to the scene. Inside the Matchbox, Akitaru requests Shinra and Arthur to hide their weapons in public. When the team arrives at the scene, Akitaru notices that both Arthur and Shinra are disobeying his orders and takes the two aside to talk, explaining that since purifying Flame Humans means killing their bodies, their loved ones also lose them forever, and tells that if a person cannot hide their weapon in the eyes of the families of victims, they have no place in the brigade. After they finish the conversation, a gigantic flame bursts out from the balcony. The brigade storms the apartment and are greeted by Mikako's father. Arthur volunteers to take care of the threat, much to Shinra's confusion. Akitaru then reassures Shinra that what they are doing is for the greater good and that the most frustrating job is to get used to it. When the ceiling of the building collapses, Akitaru jumps in to save a family picture for Mikako, with the rest of the brigade falling back to safety. In the meantime, Joker mumbles that the brigade is smoldering for a fight, while the opposing threat is just playing around. Outside, Akitaru delivers the precious memento to Mikako and assures Shinra that all they can do is to get as close to the ones who are left behind.

Rookie Fire Soldier Games
The Rookie Fire Soldier Games begins, where Shinra meets Tamaki Kotatsu. In the meantime, Maki gets fascinated by 119. She then informs both Shinra and Arthur about the guests. Later, Shinra meets Leonard Burns, and approaches him. The boy introduces himself, but the man just shoots him down and leaves. Shinra attempts to catch up to him, but is interrupted by Tamaki, whom Shinra accidentally gropes. Shinra pleads the man for his time, but to no avail. The announcer informs the contestants to gather up, which leads to Leonard telling Shinra that he doesn't remember anything and that he should just get ready for the competition, which makes Shinra wonder if the man is hiding something. When the competition starts, Shinra uses his Ignition Ability to jump onto the building with ease, while Tamaki uses Nekomata to substantially increase her mobility in order to catch up to him. Shinra ventures inside, where he encounters a strange man, who appears to know about Shinra's past.

Joker teases Shinra about his past and threatens to kill the unconscious people, but Shinra uses his abilities to make him fall back, though the man dodges all of the Fire Soldier's kicks. Joker then takes out a bottle of an unknown substance. In the meantime, Arthur cuts his way inside the building and Takeru Noto bombards the building with his Ignition Ability, which leads to Tamaki falling straight onto Arthur. Joker and Shinra continue their confrontation, with Joker causing an explosion using the powder and moving in for an attack, injuring Shinra. The Fire Soldier, fearing death, shows off his devious smile, which encourages Joker to give him a reward in the form of information that Sho is still alive. Shinra questions Joker, who encourages the boy to become a "Devil" and discover the secrets hidden by Special Fire Brigades, and attacks him with multiple fire-enhanced kicks, but to no avail. Joker notices the arrival of Arthur and Tamaki and tries to get rid of them, but Arthur quickly draws out his sword and blocks the man's attack. Shinra attempts to warn the two about the situation, but neither Arthur nor Tamaki listen and think that the man is a part of the simulation exam. The two move in for an attack, with Tamaki using her Ignition Ability to trap Joker, but he uses the substance to cause an explosion, in an attempt to get rid of the girl, though Shinra rescues Tamaki in time. Before the intruder leaves, he challenges Shinra to save everyone and releases all his powder, offering Shinra the chance to join his cause.

Shinra grabs the two unconscious people and tells Arthur to cut a hole through the ceiling, so they could escape, with Tamaki assisting him. As the powder detonates, Shinra uses his ability to escort the four people to safety, though both Tamaki and Arthur let go of Shinra in the air. Leonard jumps in to save Tamaki while the 8th Special Fire Brigade save Arthur, catching him with a blanket. In the meantime, Gustav Honda saves his newest recruit from the falling debris. After landing, Shinra is thanked by Leonard for saving Tamaki and Akitaru promises the boy that he'll reveal to him what purpose the 8th Special Fire Brigade was created. Due to these events, the Rookie Fire Soldier Games was halted and an investigation began for the retrieval of Joker.

The Sentient Flame Human
Akitaru gets approached by Shinra and the two talk about the origin of the Special Fire Brigades and how the 1st, 2nd and 5th brigades came to be. Akitaru tells him that each brigade has their own ulterior motives and are hiding something on their end, regarding knowledge on Flame Humans and the phenomenon. He also tells Shinra the purpose of the 8th Brigade. Shinra asks Akitaru to allow him in helping with the investigation, but the two are interrupted by Takehisa, who reports the results of the research on the substance Joker was using in the fray. Meanwhile, Joker discusses the events of the Rookie Fire Soldier Games and reports on the 8th Special Fire Brigade with his associate. Maki sends off Shinra and Arthur to rescue Mamoru, who was seen stuck in a tree, and when the two Fire Soldiers do, Shinra is told that the trial for the release of the convict, Setsuo, is going to be held. In the courtroom, the prisoner gets paroled due to him being insane and, as soon as he gets out, the man turns into a Flame Human. The 8th Special Fire Brigade moves out to take care of the situation.

Setsuo uses his new powers to kill innocent people and the judge in the courthouse. In the meantime, Arthur and Shinra notice the Matchbox passing through. From inside the vehicle, Takehisa scolds the two Fire Soldiers and promises to punish them. Shinra uses his ability to fly and catch up to the moving vehicle. Takehisa informs the two that a Flame Human was spotted in the courthouse and tells them to go on ahead. In the courthouse, Setsuo grabs his lawyer, but, from out of nowhere, Arthur and Shinra attack Setsuo. The Flame Human targets an innocent girl in the area for his attack, but she is saved by Maki. Realising his predicament, Setsuo tries to surrender, hoping that his life would be spared, but is shot at by Takehisa. In retaliation, he uses his flames to distract the man, allowing himself to run away. Setsuo then promises the brigade that he will kill innocent people just like Special Fire Brigades kill Flame Humans. Takehisa then asks Shinra to catch up to the Flame Human using his ability and dispose of him, which Shinra promises to do.

Setsuo arrives to a crowded location and targets an passerby for his next attack, however, when the Flame Human approaches his prey, Shinra jumps in to save the person, kicking Setsuo away with the help of his Ignition Ability. Setsuo, however, argues that he has the right to kill people and so he picks up a vehicle and throws it at innocent bystanders, but Shinra manages to jump in and kick the car away, much to the shock and horror of the Flame Human. Meanwhile, the 5th Special Fire Brigade watches the fight from a distance. Shinra begins praying for Setsuo's soul as he walks towards him, with the dedication to end the man's life, however, the Flame Human requests the luxury of having a sister pray for his soul. Using such a plea as a distraction, Setsuo attempts to attack Shinra from behind the boy's back, but the Fire Soldier quickly reacts to such an attempt and cuts off one of the Flame Human's arms with a fiery kick. As Shinra prepares to end Setsuo's life for the second time, Hibana jumps in to protect the Flame Human from further jeopardy.

As Setsuo is restrained and gets taken away by the 5th Brigade, Hibana glares at Shinra, causing him to collapse to the ground. She tells her subordinates to hold him down while she lectures the Soldier on how to be respectful towards superiors. The woman orders Shinra to lick her shoe as Shinra acknowledges that what he had done was rude and apologises, however, the woman refuses to listen and repeats her order. When a member from the 5th Brigade pushes a passerby away, Shinra, infuriated, is provoked to kick his opponents away with a twirling fire kick. He stands up and challenges the 5th Brigade to a fight as the 8th Special Fire Brigade arrives at the scene. Hibana explains that she wishes to capture the Flame Human for research, to which Akitaru responds by asking whether the information will be shared. Hibana smiles and agrees, though Akitaru sees through her deceit. As a member from the 5th Brigade mocks Akitaru for not having fire manipulation abilities, Shinra and Arthur jump in to pick a fight with the boy, they are stopped. Maki then approaches him and delivers a corkscrew punch straight to his gut, followed by Akitaru thanking his squad. After Hibana confronts Akitaru on the fact that he doesn't have any Ignition Abilities, he claims that no matter what he's opposed with, the flames of his squad will never be extinguished.