Flail

is a member of the Knights of the Ashen Flame, who formerly served as a Fire Soldier in the Special Fire Force Company 3.

Appearance
Flail is an older man with wrinkles, who ties his dark coloured hair in a bun. His most noticeable feature is his beard, which he has grown out since meeting Akitaru Ōbi. While a Fire Soldier, Flail wore his force's standard attire which included bunker gear and a helmet with his brigade's emblem on it. As a member of the Ash Flame Chivalric Order, he wears white clothing with the cross of the Sol God symbol on his chest, and also wears a hooded cape.

Abilities
In the Ash Flame Chivalric Order, Flail is recognised as an elite soldier, who specialises in combat. Being a Third Generation, he can use his Ignition Ability on his chain to create a spiked flail, which he can freely control. The weapon can range in size, from the size of a normal flail, to larger than Flail himself, which he can use to swing down onto an individual to crush and burn them.

Background
Alongside the Special Fire Force Company 3, Flail commanded his brigade when dealing with an Infernal incident. On arrival to the scene, Flail received a report of the situation from Akitaru and dismissed him. When Akitaru spoke up and questions his brigades plans with dealing with the Infernals, Flail justified their rational before departing the scene.

Vulcan's Workshop arc
After Giovanni returned from meeting with Vulcan, he tasked Flail and Mirage with killing everyone in Vulcan's Workshop, and to make it appear to be an Infernal incident. After changing out of their bunker gear and into their White Hood attires, Flail and Mirage arrive at the workshop alongside a small army of clones that Mirage created with his Ignition Ability. Arthur Boyle exists the workshop, and attacks the pair with a slash of his ignited sword, leading to Flail dodging. Questioning who the boy is, Flail uses his Ignition Ability to attack Arthur, but Arthur overpowers him with his own.

As Mirage distracts Arthur with a look-alike clone of himself, Flail attacks the distracted boy. When Giovani returns and enters the workshop, Flail and Mirage prevent Arthur from entering, but is unable to stop Shinra Kusakabe from entering. When Hibana arrives, she attacks the pair with her Ignition Ability, leading to Flail groveling on the ground. Soon after as Shō Kusakabe arrives and defeats Shinra, he orders Flail to take the teenager to the Preacher, but is immediately knocked back by an explosion coming from Vulcan's Workshop. Standing amongst the smoke, Flail ask Mirage when their targets are, to which he is told that Shō is pursing them. After the ordeal, Flail, Mirage and Giovanni leave their brigade, and go to the Netherworld.

Netherworld arc
Upon the Special Fire Force Company 8 entering the Nether World in search for the Ash Flame Chivalric Order, Mirage and Jonah separate the brigade, leading to Flail and other special elite soldiers confronting Maki Oze alone. Saying he'll show her something fearsome, Flail has one of his soldiers attack Maki, but they are swiftly defeated. As the rest of the soldiers are defeated by Maki, Flail attacks her with his flail in the name of the Preacher. Attempting to crush her with his weapon, he is attacked by Maki's Iron Owls, followed by the girl attacking him herself. Immediately after, Maki attacks Flail with her Iron Owls again, leading him to comment that her attacks won't work. Enraging Maki, she attacks him with a single strike, leading to him falling to the ground in defeat.

Trivia

 * Like other members of the Ash Flame Chivalric Order, Flail shares his name with his ability.