Fire Force season 3 episode 8: Arthur heads to Nether while the secret behind the Spontaneous Human Combustion and Doppelgangers is revealed

Fire Force season 3 episode 8, titled Holy Mother of Darkness/The Knight King's Great Adventure, was released on Friday, May 23, 2025. The episode finally revealed the shocking truth about Spontaneous Human Combustion and its connection to the Infernal Doppelgangers.

The episode further revealed Sister Sumire's actions that led to the mass Spontaneous Human Combustion incident at the St. Raffles Convent. Additionally, Fire Force season 3 episode 8 focused on Arthur, who sulked over his defeat against Dragon. However, his delusions kicked in when Vulcan told him that he would forge him a true Dragon Slayer with the real Orichalcum material.

Disclaimer: This article contains spoilers from Fire Force season 3 episode 8.

Fire Force season 3 episode 8: Hibana uncovers the truth about the Spontaneous Human Combustion, Doppelgangers, and more

Hibana, as seen in the episode (Image via David Production)

Picking up the events from the previous installment, Fire Force season 3 episode 8 commences with Hibana perplexed to see Sumire in the hidden room. Anger fuels Hibana, as she asks Sumire whether she was involved in the fire incident. Sumire replies that Hibana should already have her answers.

According to Fire Force season 3 episode 8, Sumire was responsible for using the children at the convent for his doppelganger experiments. She mixed Adolla Bugs into their vegetables and fed them to the sisters. In other words, she deceived the devoted children to turn them into pyrokinetics.

Also, the mass Spontaneous Human Combustion outbreak was one of Sister Sumire's Doppelganger experiments. Hibana realizes in Fire Force season 3 episode 8 that the Doppelgangers are another version of someone who resides in Adolla. The Adolla Bugs, or the Infernal Bugs, are the creatures from Adolla, bridging the link between two worlds.

Sumire, as seen in the episode (Image via David Production)

According to Fire Force season 3 episode 8, for every person on Earth, there exists a Doppelganger. Spontaneous Human Combustion is a phenomenon caused by their (the Doppleganger) existence intruding and merging with the real person. However, Hibana still can't quite figure out what Adolla is all about.

Sumire is intrigued by Hibana's intellect. She expected no less from Hibana to have unearthed such an answer. At this moment, in Fore Force season 3 episode 8, Huo Yan Li senses an Earthquake. Yet, he doesn't understand what's causing it. Meanwhile, Hibana asks Sumire about the Pillars. Sumire replies that thanks to her experiments, all the Pillars have been assembled.

Hibana doesn't understand what Sumire means here by "assembled." At this moment, she realizes, to her shock, that Iris is one of the Pillars. Hibana is speechless at Sumire's actions. She can't fathom how many orphans' lives she has toyed with for her experiments. Yet, Sumire doesn't say anything, but she emanates a murderous aura.

Adolla, as seen in the episode (Image via David Production)

While Karim and Huo Yan Li prepare for the fight, Hibana persistently questions Sumire about her actions. She asks whether the convent was a lab for experiments before she raised the sisters. Meanwhile, Sumire charges at Huo Yan Li and deals a heavy blow. She goes after Karim next, but she steals the heat from Sumire's hands.

Sumire is impressed by Karim's powers. She mentions that Rekka was incredibly energetic as a child and harbored a strong sense of justice. Karim can't believe that Sumire raised Rekka as well. Hibana then asks Sumire what she intends to do. At this moment, Sumire reveals her actual goal.

According to Fire Force season 3 episode 8, the Great Cataclysm 200 years ago was a failure because it had neither the number nor the strength of the necessary Pillars. As a result, the world was left in cinders. Since that failure, Sumire has been continuously making Pillars for the next Cataclysm.

Infernalized sisters, as seen in the episode (Image via David Production)

Multiple questions begin to swirl in Hibana's mind. She wonders whether Sumire is over 200 years old. At the same time, Hibana asks the sister whether Spontaneous Human Combustion existed before the Great Cataclysm. She also wonders what the Great Cataclysm is all about.

At this moment, in Fire Force season 3 episode 8, everything became clear to her. If Spontaneous Human Combustion is the Awakening of an individual by merging with their Doppelganger, the Great Cataclysm is the merging of Adolla and the world. Meanwhile, Huo Yan still experiences unending Earthquakes.

As for Hibana, she still cannot digest the truth. She wants to exact revenge on Sumire, the person responsible for stealing the lives of her beloved friends. However, Sumire says that they aren't "dead." At this moment in Fire Force season 3 episode 8, Sumire raises the infernal versions of Hibana's old friends. One of them happens to be Sakura.

Sumire and Amaterasu (Image via David Production)

Meanwhile, Huo Yan Li engages in a combat against Sumire. Yet, as soon as he touches her, his hands get injured. Hibana and others realize that Sumire can create vibrations using her body's shivering. She uses her ability to amplify the heat and turn it into Kinetic Energy. In other words, the Earthquakes are the result of her bodily vibrations.

Furthermore, she uses the Adolla Burst to amplify her powers. At this moment, Kishiri blows up the ceiling to ensure Hibana and others can get out. Sumire becomes furious and wants to teach them a lesson. Yet, before she can do that, she experiences an Adolla link with Amaterasu.

While she's in Adolla, Hibana and others escape from the scene. Meanwhile, Sister Sumire returns to the darkness to enact her role as the Seventh Pillar.

Fire Force season 3 episode 8: Arthur's great adventure begins

Arthur and Vulcan in the episode (Image via David Production)

After returning from the convent, Hibana is engrossed deeply in her thoughts. Recounting the truth she has uncovered, Hibana realizes they must work together to prevent another Great Cataclysm from happening. Elsewhere, in Asakusa, Arthur Boyle appears down after his defeat against Dragon.

He holds a piece of his "Excalibur," and thinks it's truly meaningless. Vulcan checks the piece of Arthur's Excalibur and realizes it's only a fire-resistant carbon that can be found in any hardware store. However, Arthur believes it's Orichalcum, a metal of legend.

At this moment, in Fire Force season 3 episode 8, Vulcan decides to play along with Arthur's delusions. He tells him that it's not the real Orchalchum, but a fake one. He asks Arthur if he would like to go and find some real Orichalcum. Once they find it, Vulcan plans to forge a real Holy Blade. Arthur buys Vulcan's words and decides to follow him.

Arthur, Vulcan, Lisa, and Yu (Image via David Production)

Meanwhile, Vulcan informs Yu and Lisa about the whole situation. He also urges them to play along with Arthur Boyle's whims. To satisfy Arthur's knightly ego, Vulcan comes up with a terrific plan. He tells Arthur that a pickle shop owner has the clue to the real Orichalcum's location.

At first, Arthur doesn't believe in Vulcan's words. However, when Vulcan reminds him that a pickle-maker weighs down the pickle press with "stones," the boy somehow realizes that it could be true. Eventually, the party heads to the pickle store. Interestingly, the shop owner informs Arthur that the Orichalcum he is looking for is at the Kimono Dealer's shop.

Arthur Boyle, as seen in the episode (Image via David Production)

Apparently, it's all part of Vulcan's plans. He has already given the Pickle Store owner a hunk of steel. Furthermore, Vulcan has made an adventure guide for Arthur, filled with multiple clues to the Orichalcum's location. Yet, it's made in such a way that it should eventually lead Arthur to the pickle store at the end of his journey.

Meanwhile, at Asakusa, Benimaru Shinmon and Joker converse about the country's safety. Benimaru believes that the whole country itself is a lie. He wants to rip everything powerful than him to pieces. And yet, he knows that Company 8 is gearing up for a fight. As such, he realizes that he doesn't have much of a choice but to join them.

Arthur embarks on a new adventure (Image via David Production)

Elsewhere, in Fire Force season 3 episode 8, Arthur collects a few important clues on his quest to find the Orichalcum. In the final hurdle, he finds a cryptic note, instructing him to go to the first shop he stopped by, i.e., the pickle store. Yet, instead of reading that, Arthur's eyes go to the first line, which reads that it's the darkest beneath the lighthouse.

Suddenly, everything becomes clear to Arthur. He realizes the Orichalcum must be in the Nether. Vulcan, Lisa, and Yu can't believe the extent of Arthur's delusions. Fire Force season 3 episode 8 ends with Arthur Boyle ready to go onwards to the Nether.

Conclusion

Fire Force season 3 episode 8 has finally answered the truth about the Spontaneous Human Combustion and the Doppelgangers. Although it came from an unexpected source, it has nicely set up the stage for the remainder of the narrative. At the same time, the episode featured comedic scenes, with Arthur's delusions going haywire.