Pillar

A is a pyrokinetic individual who possesses an Adolla Burst. They are each protected by a Guardian from various organizations.

Adolla Burst
The Adolla Burst is a flame that originates from the realm of Adolla, also known as hell. The exact nature of the Adolla Burst remains unknown, however it has been referred to as a "pure and unsullied flame".

It is being in possession of an Adolla Burst that makes someone a Pillar. The Adolla Burst greatly enhances their pyrokinetic abilities, allowing them to achieve feats that would otherwise not be possible.

Great Cataclysm
It was the flame of Adolla that burned across the world during the Great Cataclysm. It was meant to completely burn the world to ashes, but the endeavor was a failure due to the number and strength of the Pillars at the time. It is theorized and confirmed if the current eight pillars come together with the Evangelist, a second Great Cataclysm will occur. Each of the Pillars embodies a different negative human emotion. These emotions, born from humanity themselves, are what fuel the fires of the Great Cataclysm.

Sumire experimented over two hundred and fifty years to have all the Pillars assembled, with the Eighth Pillar being the final one, in order to successfully recreate the event.