A Tuner (調律師 Chōritsu-shi ) is a Flame Haze that has the ability to perform the task of Tuning, which is often needed to lessen the effects of a large amount of Distortions as a result of many Torches being created. The only known tuner is Khamsin Nbh'w.
Normally, Tuners are Flame Haze who live through countless battles with their desires for vengeance against Crimson Denizens worn out or were already fulfilled. These handful of Flame Haze, who did not commit suicide by revoking their contracts, would choose to perform Tuning as their new duty.
Tuners are not to be underestimated as most of them possess very powerful strength that they had been utilizing prior to working as Tuners. Also, Tuners are specialized in searching for places where huge Distortions occur. As the results of their active Tuning task, harmful catastrophe has been averted until present time.
The never-ending battles between Flame Haze and Crimson Denizens often cause the loss of lives and widespread structural damage. However, since the introduction of the Fūzetsu, Flame Haze can easily repair the damage done to a certain area by using Power of Existence and the production of Torches to dampen the effect of the disappearance of existences during battle. Despite this, most Flame Haze are not fully equipped to counter the long-term effects of this cycle of destruction and repair, especially on places which have been the center of battle for prolonged periods of time, like Misaki City and the city of Osterode.
Tuners are given the special task of fixing the Distortions created by continuous warfare among the two sides, and a necessary aid to rehabilitate places which have been the battlefields of past events.