Works where the "Demon King" MUST be summoned
 

I was wondering, are there any anime/manga where it is actually necessary to allow the ultimate evil to awaken? I'm not talking about a not-so-evil being like in a recent Demon King anime. I'm talking about a living death, a pure manifestation of doom and destruction; the sort of creature you usually don't actually see because the only way to win is to KEEP it from awakening.
An example might be a case in which such a creature's awakening is thought to be inevitable in the very distant future, and the only chance to stop it is to find some way to awaken it prematurely under circumstances that might just weaken it, or where its continued presence in eternal slumber is having some sort of effect, or perhaps its continued sealing requires a heavy price.
And it doesn't have to be definitively stated whether it's legitimately necessary for the beast to be freed if good is to win, so long as someone, good or bad, believes so and his argument is sound enough that it's a definite possibility.

There's plenty of stories out there where someone's trying to summon such a "god", but pretty much when this happens the ultimate villain is never seen because the good guys stop it from awakening, or if they don't stop it it's clearly a bad thing no matter how you slice it, and it's only through a desperate last gamble that they manage to stop it, often by returning it to sleep again rather than killing it.

I can only think of one such story off the top of my head that comes close to this scenario:

I think something like that happens at the end of Psychic Detective Yakumo.

It was kinda the point of Casshern Sins except you have to replace Demon King with mortality. That's a bit of stretch though.

RAVE comes to mind, with Endless playing the role of living death from another plane...

Demon Lord Dante plays sorta on that

Kannazuki no Miko's plot is very much containing of this, and drives one of the characters to want to awaken it.

Not anime: the works of H.P. Lovecraft, the Cthulhu Mythos.

I've been thinking of this anime but couldn't remember it clearly, and it seems you got it first Konakaga :heh:

uhh yeah i agree that Devil may cry had that, only other thing i can think of is Unicron in Tranformers movie (or Deathsaurus' Space fortress) >_< but im sure that not what your looking for

also havnt finished Scrapped Princess, lol, so I dont know the ending, but she is the "Doom of the world" so to speak when she turns 16 i believe

Scrapped Princess only fulfills the OP's requirement if you don't actually know what Pacifica is and what happens at the end...

... but if you know those things, it's not what the OP wants. :heh:

I'm not sure about Kannazuki, but it's been a long time since I saw it. I thought that the evil came forth of its own accord and one character sided with it to force another character to end things a certain way.

The evil had started to appear because the previously place seal that had been started to weaken, thus it it needed to be resealed or else it would be summoned in Kannazuki no Miko ;). And that character did so because of the price of resealing it.

how about naruto, he has evil thing inside him

Yes he does, but his goal is to either keep it sealed or control it somehow and take its power from it so that it can't cause harm. I'm looking for something where the ultimate evil is lying dormant, possibly without any real sign that it will awaken soon, and someone specifically tries to awaken it and break its seal out of some sort of necessity.

One example scenario, though I don't know that I've seen something like it before, would be

Im surprised no one has said this, but i think Kaze no Stigma would pretty much cover it. thruought the storyline there are many "Summoned Demons" but they dont compareto the final one. it fills the criteria within a timely manner.

Say Hello to Tears to Tiara. Though it's rather a subversion because the Demon King IS the main protagonist lol. The role of the text-book Demon King falls to the Angels there.

How about X from Clamp?

In a way, Fate kinda fits to this.

Probably this wasn't mentioned because, if I recall correctly, there wasn't any real need for the summoning to take place. As I stated, I'm not just looking for stuff where the ultimate demon is summoned, but stuff where there's some good, valid reason for the summoner to believe that it must be summoned, or that leaving it sealed will result in untold pain and tragedy, but even the summoner understands that the being is evil and must be destroyed.

Actually I think this is kinda what The Wheel of Time series is leading up to. That's a book series though.

Ahh thanks for the correction

I think that one manga that required an ultimate evil to awaken was 666 Satan, otherwise known as O-Parts, if I'm not mistaken.