Introduction arc

This arc takes place, beginning from chapter 01 to the current chapter.

Summary
On a train, a human is set ablaze while at the same time, Shinra Kusakabe makes his way to 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 and announces that a train was caught in fire, after which, people begin evacuating the premises as a Flame Human appears from the train carriage. Before Shinra could take action, the 8th Special Fire Brigade arrive. The brigade confronts the being, eventually managing to destroy its core. After the ordeal, Shinra notices a falling light and uses his ability to save the person underneath and introduces himself as the team's newest member to the brigade. When the team returns to their base, Shinra is formally introduced to Takehisa and Akitaru. When asked why he joined the brigade, Shinra replies that he wants to become a hero. After the girls have a shower, Shinra is introduced to Maki and Iris. The brigade members soon begin talking about the Human Body Ignition Phenomenon and that their mission is to unravel the mysterious surrounding it. Later in bed, Shinra recalls the death of his family and claims there was a "black shadow" present before they died, as well as how his grandma treated him following the incident. Straight after, he and the team are notified that a fire has broke out and the team gets prepared and departs to the scene, where Akitaru encourages Shinra to do his best while on the job.

Shinra goes on his first official mission with the 8th Special Fire Brigade, where the wife of the factory's manager has become a Flame Human. After arriving on 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 is 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 out, 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.

Akitaru informs Shinra that a battle tournament will be held between the newcomers of all eight Special Fire Brigades. Meanwhile, Arthur arrives at the 8th Special Fire Fighting Church. Shinra, excited to see the leader of the 1st Special Fire Brigade, the man who saved him in the past, bumps into Arthur while waking through the corridor. On the roof, Maki shows Iris how she can create sentient flames, but their conversation is cut short when a fight breaks out between Arthur and Shinra. The former unsheathes his bladeless sword, which causes Maki to question his weapon, to which the boy responds by introducing himself as the "Knight King" and calling the two girls "princesses". Shinra and Arthur start squabbling again, but it is cut short when Takehisa arrives to see what was behind all the ruckus, pouring some water on Maki's fireball and telling her not to play with the flames. The commander orders Maki to fight the two boys, with the girl asking the two not to underestimate her, quickly disposing of Shinra. Maki then attempts to extinguish Arthur's Excalibur, but fails. Using her combat skills, she makes the boy kneel before her, kicking him in the face with her knee, causing Arthur to insult Maki, which forces her to create a huge creature out of the flames of both Arthur's sword and Shinra's flames. After the battle, Shinra is baffled and thinks to himself that he needs to become stronger, so that he can protect people when the time calls for it. In the meantime, Takehisa extinguishes Maki's creature, much to her horror, and Akitaru, who has been lifting weights this whole time, ponders about how long will it take for Arthur to arrive.

Shinra, Arthur and Akitaru eat at Ippudo Ramen, where the two Fire Officers fight on who can finish their meal first and afterwards, on their way back to the headquarters, Arthur has a casual conversation with Akitaru, which makes Shinra notice that the Battalion Commander is a very nice person, impressing the boy that Arthur is getting close to him in such a short amount time. Back at the headquarters, Takehisa gives Shinra a seven-style battleaxe, and offers Arthur one as well, but he refuses to accept it, viewing Excalibur as the only weapon he requires. Akitaru then complains about the maintenance and wishes that the brigade had a mechanic in their ranks. In the meantime, Mikako returns home, only to see her father has turned into a Flame Human. The siren signals a mission, which forces Maki to gather up the team and head out. While in the Matchbox, Akitaru requests Shinra and Arthur to hide their weapons in public. When the team arrives at the scene, Akitaru starts feeling pity for Mikako. He then notices that both Arthur and Shinra are displaying their weapons in public, and takes them aside to have a talk, telling them that, since purifying Flame Humans means killing their human 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 8th Special Fire Brigade. After they finish the conversation, a gigantic flame bursts out from the balcony, forming into a smiley face, to which Maki claims it not being her doing while Shinra questions if it's the work of the Flame Human inside the house.

Two unknown men are ecstatic that their plans are in full fruition. In the meantime, the 8th Special Fire Brigade storms into the building and, as they step foot in the house, they trigger some sort of powder on the floor. The brigade gets into the room, where they spot a Flame Human, casually sitting in a chair, and Akitaru notices the picture of Mikako's family. Arthur volunteers to send away the Flame Human, but Shinra tells him that the being has done nothing wrong, however, Akitaru reassures Arthur to go, with the boy claiming that the man must be in pain from all the fire. The rest of the brigade start praying as Arthur impales Mikako's father with his Excalibur. 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. Takehisa then notices powder, seeping from the ceiling, as the roof collapses straight on the brigade. Akitaru ignores safety precautions and runs straight for the Mikako's family portrait, but gets rubble fallen on his body. The man, however, dedicated and furious, exclaims that he has been training for this every day. In the meantime, a shady character, smoking a cigarette, mumbles that the brigade is smoldering for a fight, while the opposing threat is just playing around. After reassured that Akitaru is fine, the brigade moves out of the building. While outside, Akitaru delivers the picture he managed to save to Mikako, telling her that her parents were fighting for her sake. Shinra apologizes for not being able to do anything, while Akitaru just assures him, and everyone else, that all they can do is get as close as they can to the ones who are left behind.