THE PLOT

Ok, for anyone confused about the plot, here I'm copy pasting my earlier explanation aka summary (or at least, what I *think* is going on....) and if I got anything wrong, feel free to correct anything!:

It seems like every few generations there appears only one purifier and five unique and powerful "demonic" mages who are human but possess demon magic to manipulate the elements and who are usually recruited to work for the rulers of each of their countries. However, their magic has lethal side effects and they depend on the purifier's "healing" powers to help them survive those side effects. Out of the five mages, four mages are each able to control one of the four elements, while the fifth mage can manipulate all the elements controlled by the other four. Being as unique and powerful as they are, the mages may be feared by rulers and kings, who try to impose their control on them, and they're also feared and hated by the church, and within the church, by the priests and by the head of the church, the pope. That is because the priests' and pope's magic comes from angels whereas the five mages' magic comes from those angels' enemies, the demons. The purifier's healing power, on the other hand, apparently comes from a fallen angel who joined the enemy demons.

Each of the purifier's five mages is in such desperate need of the purifier's help (to survive their demonic magic's side effects), so much so that they might even become willing to fight among themselves or kill one another, in order to see who among them gets to be the one to keep and monopolize the purifier, along with her "healing" power (and, the safest way to make sure they'll always monopolize her power, is to actually eat her body like she was food). Knowing of this eternal rivalry present in each and all generations of mages, the five mages are compelled to distrust one another's willingness to "share" the purifier, and so each one feels threatened by the existence of the other four. Thus, once they discover they're one of the five, they might even choose to keep their identity a secret.

At the present, they only know the identity of three of these mages: one is the male lead (the one able to control the four elements at the same time, who is being forced to use his magic to serve the emperor, but is secretly planning to rebel), another one is the emperor's own son, the crown prince (who is probably the water mage, and who obviously uses his magic to the benefit of the empire), and a third one works for a foreign country (the earth mage). The identity of the other two mages is currently unknown, but our main character, Ertha, already knows (due to the novel) that those two are actually her own siblings, the twins, who have yet to awaken and discover their magic: her little sister is the fire mage while the little bro is the air mage.