Return to St. Raffles arc

The Return to St. Raffles arc is the seventeenth story arc of the Fire Force manga series.

Summary
Following the death of Leonard Burns Company 5 Captain Hibana and the Lieutenant of Company 1, Karim Flam and Foien Li, both travel to St. Raffles to uncover the truth. Each seeking more information about doppelgängers based on their research into Infernals and Rekka Hoshimiya.

After praying to her departed sister and telling Tōru Kishiri to stay put, Hibana goes inside the ruins and finds a hidden pathway underneath the altar. Unable to move it on her own, Karim and Li offer to aid her after Kishiri let them pass. After some bickering they uncover the hidden passageway to the Nether. In the basement they find 8 stone pillars, basement, research materials on botany, agriculture, insects and cookbooks. While Flam is confused how any of this relates to doppelgängers, Hibana begins to sweat. Remembering the flower gardens, the crops grown for food at the orphanage and the the sister's warnings about nearby insect hives. Almost vomiting, she realizes that the sisters of St. Raffles were all experiments. Secretly fed food mixed with Fire Bugs to create doppelgängers and pryokinetics. Her suspicions are confirmed by a figure emerging from the shadows: Sister Sumire. Still alive and unaged.

Stunned and confused by Sumire's survival and involvement, Hibana demands answers. Accusing Sumire's experiments as the reason behind the mass spontaneous human combustion incident and asking what the Adolla is. Proud of her student's growth, Sumire admits to everything and boasts her experiments have created the last of the Eight Pillars. She tells the trio that the Eighth Pilllar is the unaware SIster Iris, who is also a doppelgänger of The First. Distracted by a sudden earthquake, Li is quickly attacked by the woman and she instantly destroys Karim's instrument despite his attempts to freeze her hands. While using her abilities to seriously injure the two men, she explain Rekka's childhood. Hibana, still confused and furious, vows revenge for the death of her sister. Only for Sumire to ask her: How can she be sure they are really dead?

Demon Infernals begin to crawl out of Sumire's shadow: the doppelgängers of the sisters killed in the fire and Hibana's childhood friends. While Hibana is shaken and Sumire is distracted, Li tries to attack from behind but the intensity of Sumire's vibrations damage his arm upon contact. This causes the three soliders to recognize that the nun's power involves manipulating shivering and vibrations with the Adolla Burst making it more powerful. Before they can be killed by the Sister, Kishiri blows out the ceiling and opens an escape route. Before she can attack her escaping enemies, Sumire is pulled into an Adolla Link by The Woman in Black. The Woman's warns Sumire that the world will not be changed by the Evangelist's plans before fading away. Sumire says goodbye and promises to fulfil her role as the Seventh Pillar.

Having escaped the Seventh Pillar; Hibana, Li and Flam compare information. Infernals are the result of doppelgängers fusing with humans and the Great Disaster was a result of the Adolla Realm itself trespassing on the world. With Eight Pillars with Adolla prepared, a Second catastrophe is inevitable. If the world is to be saved then everyone must work together.