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The Demon King (also translated as Demon Lord or Archfiend) is the title given to the ultimate life form on the Continent, maximum ruler of The Monster Realm and the most powerful being in the continent. It's the sole being in charge of the antagonist race, the "big bad" of the continent and exists solely to create destruction and disorder. Humanity's greatest dream is to is to permanently defeat the Demon King to be free. The calendar system used in the Rance World uses the name of the ruling Demon King to mark the era. They have an almost uncontrollable blood lust and hate for the Protagonist Race, although it varies depending on how strong the demon king is and on his/her personality. Demon King Gele had the most intense bloodlust, while others like Gi or Ssulal barely acted against humanity. This intense hate is a feature created as a part of the system put in place by the Three Supreme Gods, designed to appease Ludo-Rathowm's childish desire for entertainment through chaos. Obviously there can only be one demon king at the same time and their era lasts until they die.
The Demon King's blood is special. It's the source of the demon king's power and what actually crazes them and fills them with thoughts of malice and destruction towards the protagonist race. If any other creature or living organism consumes the demon king's blood in any way, they turn into what it's known as a Dark Lord (also translated as "Demons" or "Fiends" sometimes). At any given time, only 24 Dark Lords can be created, and since each Dark Lord carries the blood of the demon king within their veins, they are tied to a blood pact that makes impossible for any dark lord to disobey a demon king. Naturally, in exchange, the demon king's blood grants the dark lord with immense power, allowing the Demon King to make a group of extremely powerful beings. The downside for it is that each Dark Lord created weakens the demon king a bit, although the difference is not even noticeable for humans.
Powers and AbilitiesEditThe Demon King is the most powerful creature in the continent, far beyond any other living being. They surpass with ease the strength of a 2nd Class God although they don't quite reach that of a 1st class or a Devil Prince. Humanity is absolutely powerless towards the might of the demon king. Good examples of this are Nighcisa, who easily slaughtered half of the entire human population with little effort, and Gele, who destroyed every human nation as soon as she turned into the Demon King.
The Demon King craves blood, and has the ability to drain blood from its enemies. The more powerful the Demon King, the more intense the desire for blood becomes. No matter how nice or peaceful someone is, if they are turned into the demon king, they will become savage monsters that wish nothing but destruction. This effect is more or less intense depending on the strength of the demon king and their initial personality, but their blood lust is always powerful. However, the Demon King's transformation can be suppressed by consuming Hirami Lemons, a very special and limited fruit that restrains the Demon King's power, blood lust and personality but has to be consumed on a daily basis and they lose efficiency over time. Currently Miki Kurusu is suppressing the Demon King's persona through the use of Hirami Lemons.
From a request made by Ssulal, the Demon King was granted an invincibility field, a kind of magical skintight body casing that prevents the Demon King and Dark Lords from taking any kind of damage. The Dark Lord's Invincibility Field is in fact an extension of the Demon King's. The trade-off for the Invincibility Field was that now Demon Kings have a fixed ruling span of 1000 years, and must find a successor before that time is up.
While the Demon King is extremely powerful and usually unmatched by anyone, Dragon King Magiihoa(noted for being the strongest dragon of his time) was capable of defeating Demon King Avel in an encounter, even if Avel was particularly weak for Demon King standards. Also Demon King Ssulal was a very fragile person with a weak body and, while the actual extents of her powers are unknown, the fact that she was always concerned by her own safety and that she requested an invincibility field seems to imply that she could have been defeated by humans.
After a period of 1000 years have passed, the Demon King must choose a successor, it is typically given a 15 year grace period for this to happen. Ideally, the successor should be someone with an innate talent for destruction, typically this kind of person is born only once every 100 years.
If a successor is not secured during this grace period, the Demon King will lose its Invincibility Field and blood control ability over Dark Lords, and will begin to lose its powers one by one over a period of 50 years, ultimately leaving them completely vulnerable. If a successor still hasn't surfaced after this happens, Planner will select a new successor and bathe them in the blood pool. When a successor is selected by the current Demon King, the process for the succession is a special blood ritual where the chosen one receives a large amount of blood from the Demon King. At the end of the ritual, the former ritual loses all his power and is reduced to his original race, be it a human or whichever, and the new host becomes the new Demon King. Without the blood and status, the personality of the former Demon King will revert back to that of his/her original self and get to live a few more years like any regular mortal.Because the blood is always retained, the Demon King will always have the blood of its predecessors running through its veins, allowing it to keep control of any subordinates the previous Demon King may have acquired. A Dark Lord is capable of killing the demon king and consume their blood to become the demon king themselves. However, this is obviously almost impossible to achieve since the blood control ability makes it impossible for Dark Lords to disobey the demon king and even if it wasn't, the Demon King is far stronger than any Dark Lord.
The only time this was seen was when Gi betrayed Gele to become the Demon King, but this was a special case, since Gele was greatly weakened to 5% of her full strength and certain factors allowed Gi to go against the blood control ability.
A non-canon example of this was seen in Kichikuou Rance, where there's an alternate route where Kayblis captures Miki Kurusu and kills her to become demon king himself, but this was only possible for him because Miki suppresses the Demon King personality by consuming Hirami Lemons, disabling the blood control and the Demon King's power.