Quinella

Quinella is the actual ruler of the Underworld as the highest minister of the Axiom Church.

Background
She was born 350 years before Kirito enters for second time to the Underworld, she was the product of a political marriage between strong families at that time, her father was the lord in charge of the, at that point, Town of Centoria, and was the one who gave the Sacred Tasks, to maintain power in the family he created and bestowed upon her a new Sacred Task: Sacred Arts Research.

She discovered new sacred arts that the other Underworld Residents didn't know, she even discovered the Thermal Arrow command, and discovered that if you kill any other living being, your stats will rise, so she escaped every night to hunt nearby animals and rose her stats at an incredible rate.

Taking advantage of her knowledge, she made people believe that she was gifted by gods, and took the opportunity to start creating the Central Cathedral, and with it, the Axiom Church. She created the Feudal System in the underworld by making the lords into nobles and thus creating a structure to control the entire Underworld.

As her power grew, so did the tower in the Cathedral, when she was reaching her 80's she became anxious because despite all her power, her life continued to drop, until one day she managed to find a command that allowed her to see the list of all commands accessible in Underworld, in which was one that gave her all the authority from the Cardinal System and so, she became immortal.

The restriction imposed by the Axiom Church on lowering the life stats of living beings was created by Quinella to prevent other humans from grinding their authority levels.