The Demon King of the Sixth Heaven, Oda Nobunaga. Her Spirit Origin possesses what could be called the combination of all possible Nobunagas, past, present, and future.
This extremely unique Heroic Spirit's formation was said to only be possible in a certain dimension, but for some reason she has managed to manifest here.

Height/Weight: 154cm, 43kg (Changes depending on her form)
Origin: History
Region: Japan
Alignment: Chaotic-Balanced
Gender: ?
"By the way, the me that comes out right after is about 165cm, while the biggest me is about 180cm tall. Am I a model or something!?"

Oda Nobunaga. This version is closest to the real Nobunaga's Spirit Origin... Maybe not the most accurate way to put it, but let's just say it is for convenience's sake.
They may have been summoned as an Avenger, but they are closer to their Archer self.

Yet as the enemy of the gods, Buddha, and all creatures, the multitudinous grudges and terror harbored within their body was too much to handle even as a Heroic Spirit, since the Spirit Origin was originally just from an ordinary human. Thus, undergoing multiple Ascensions enabled multiple aspects of Nobunaga to develop. Calling it a multitude of possibilities emerging may sound good on paper, but what actually happens is that one vanishes every time these divergences happen. Nobunaga figured this out, but does not bring it up.

As to armaments, they have gained mysterious weapons like the ultra matchlock rifles and something that resembles a Demon King gatling gun. Don't you think a rotating, rapid-fire matchlock is absolutely badass!?

"Well, whatever form I take, don't you think I'm still the most adorable one out there? And actually, don't you think the biggest me's kinda scary?"

Oda Kippoushi. The name Kippoushi was Oda Nobunaga's childhood name. Since childhood, his peculiar behavior led to many calling him a fool.

This is the form of the young gallant warrior, the most dangerous he would be during the life where he earned his nickname "The Fool of Owari." The ambition and passion positively radiating from him faithfully represents the Spirit Origin of Nobunaga the mercenary.

Also, the sword hanging at his hip is the sword he seized from Imagawa Yoshimoto at the Battle of Okehazama, named Souza Sanmonji.

"Actually I never called myself Kippoushi during that time. But then again, this is probably an easier way to know that we're in this interesting situation where there are other Nobunagas other than me. Wahahahaha!"

Can't Be Helped: A-
This skill is a double-edged sword, burning the body up in exchange for a powerful release of magical energy. Did this judgment of their own fate disappear among the flames, or did it...?

It Is But a Dream: B
The existence of Demon King Nobunaga is a hollow one, due to the Counter Force constantly working against their powerful and heterogeneous state, which makes their Spirit Origin hazy and undefined as well.

Demon King of the Sixth Heaven: EX
A monster whose past was distorted by their reputation in life. Those who possess this skill will change their abilities and appearance. It is very much like the Innocent Monster skill. This is a skill that points to Oda Nobunaga, the Demon King of the Sixth Heaven, an entity completely different than the Demon King Mara from Buddhism.

『Pāpīyas Reborn, Demon King of the Myriad Heavens』
Rank: A-
NP Type: Anti-Divine
Range: 1 - 99
Maximum Targets: 1000

Hajun Henjou, Sanzen Daisenten Maou.
An aberrant form that contains all the fear and reverence for Nobunaga held by all creatures past, present, and future. That power now surpasses even that of the real Demon King of the Sixth Heaven. Nobunaga transforms into the true demon king, the Demon King of the Myriad Heavens that destroys various deities and Buddhas. This is the final form of the crimson Anti-Hero that incinerates the divine. This is Demon King Nobunaga.

Since this form did not exist in history, the existence itself is unstable, and so the manifestation only lasts a short while.