Demons have their elites named the Twelve Demon Moons, divided further into Upper and Lower Moons, clearly delineating their strength and rank.
The Demon Slayer Corps follows a similar notion, with ranks based on status and varying strengths.
The Ghost Hunters belonging to the Demon Slayer Corps are generally classified into ten grades from A to J, with A being the highest and J the lowest. The higher the grade, generally the stronger the member is and the better their treatment, status, and influence within the corps.
However, class A isn't the highest rank within the Demon Slayer Corps.
The Demon Slayer Corps has one leader and nine Pillars.
The leader commands the entire Demon Slayer Corps.
The Pillars are nine highly revered swordsmen who support the Demon Slayer Corps and are stronger than anyone else within the corps.
They are named after the breathing styles they use.
